CRREL hot water drill ring to drill a 1 m diameter hole in a 4 m thick multiyear ..... than 35 long-term drifting ice camp expeditions have been attempted all over the ..... the two units, makes signals to the satellte visible from virtally any angle the ..... II (2461. 12 (24611. Ice Thickness .. 3.7 m. Figure 6. AEB. 13 (24621. 25. " 10.
WHOI-90-02 COPy i
Woods Hole
Oceanographic
Institution
l
~ 1930
The
Arctic
Envi.ronmental Drifting Buoy
Report of Field Operations and Results.: 1987 ~April 1988 .
(AEDB)
August
'by SusumuHonjo, Richard Krishfield, Albert Plueddemann January 1990
Technical Report Funding Yiasprovided by the Office through
of Naval
Research,
grant Number N00014-87,88,89, J-1288.
Approved for public release; distribution unlimited.
. ~ ". . ..
DOCUMENT LIBRARY Woods Hole Oceanographic Institution
ì
WHOI.9O-02
The Arctic Environmental Drifting Buoy (AEDB) Repor of Field Opertions and Results: August, 1987 - Apri1988 by
Susumu Honjo, Richard Krshfeld, Albe Pluedeman
Woo Hole Ocogrphic Instituon Woo Hole, Massachusett 02543
Janua 199
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Technical Report Fundig was provided by the Office of Naval Research, though grant Number NOOOI4-87,88,89, 1-1288.
Reproduction in whole or in par is permtted for any purose of the
United States Government This report should be cited as: Woos Hole Oceanog. lost. Tech. Rept., WHOI 90-02.
Approved for publication; distrbution unlimited.
Approved for Distribution:
~(J~
David A. Ross, Chairman
Deparent of Geology & Geophysics
Highlights of the 1987.1988 AEDB Experiment · The desire to develop a multi-sensor automated station which could be deployed as an ice-tethered mooring system, survive in Marginal Ice Zone (MIZ) conditions, and also function as a surface float in the open ocean for a short period of time prior to retrieval, was realized in the Arctic Environmental Drifting Buoy (AEDB). · The drift track of the AEDB closely followed the predicted track within the expected time, based on previous Transpolar Drift work and models.
· For deployment of the AEDB mooring line, a method was devised using a CRREL hot water drill ring to drill a 1 m diameter hole in a 4 m thick multiyear ice island. While the bow crane of the FS Polarstern was used for removal of the ice plug in this instance, other means could be used in other
circumstances. · The ARGOS location system was used not only to determine the position of the buoy during the experiment, but also to telemeter essential engineering data. Due to the polar orbits of the ARGOS satelltes, 94% of the received transmissions were spaced less than 105 minutes apart. Characteristics of the drift, including speed, were calculated from the locations. · The temperature, strain gauge and battery information telemetered from the surface sphere was necessary for the near real-time determination of the physical condition of the surface float in the ice and ocean. Furthermore, these observations are being used to improve the design of the surface float as part of the 1991 Ice-Ocean Environmental Buoy Project (IOEB).
· Data from ice thermistor chains was collected by a loggerin the surface float until the icefloe broke apart. Upon retrieval, this information was used in the calculation of oceanic heat flux between the ocean and ice (Perovich et aI., 1989).
· Nearly 500 kg of internally recording mooring instrumentation hung below the AEDB sphere. Valid data was retrieved from two fluorometers and an Acoustic Doppler Current Profiler (ADCP), but not from a CIT recorder and a seawater thermistor logger which both malfunctioned. The ADCP results will be used to investigate the climatology and dynamics of internal waves under the sea ice.
· The deepest segment of the AEDB mooring system was lost during the drift, consequently data from those instruments were not recovered. In the IOEB experiment, almost all of the instruments on the mooring line will be configured to transmit their data via ARGOS.
Table of Contents List of Figures and Tables
ii
Acknowledgements Abstract
iii
1. Introduction
2
2. Description of the AEDB
1
10
a. Overview
10
b. ARGOS Platform Transmit Terminals (PTTs)
14 16 .19
c. Temperature and Conductivity Measurements
d. Ice Thermistor Chains e. Fluorometer Packages 1. Current Measurements g. Sediment Trap / Micro-filter Pump / Transmissometer 3. Deployment, Drift, and Recovery a. Deployment operation b. Drift summary c. Recovery operation
4. Results Appendix A: Campbell data logger program Appendix B: Fluorometer and data logger tests Appendix C: Schedules for sediment trap and micro-filter pump
References
21
22 24 27 27 28 33 35 122 124 125 126
i
List of Figures and Tables
Fig. 1 - General ice flow pattern in the Arctic Basin 3 Fig. 2 - Drifts of the buoys in the Arctic Ocean Buoy Network for 1979 6
Fig. 3 . AEDB schematic 11
Table 1 - Deployment parameters 13 Fig. 4 - Sensor positioning on buoy sphere 15 Fig. 5 - PIT sensor wiring diagram 17 Fig. 6 - Temperature and conductivity sensors / Ice thermistor chains 18
Fig. 7 - Wiring diagram for Campbell data logger 20
Fig. 8 AEDB drift track 29 Table 2 - AEDB drift regions 30 . Fig. 9 - January temperature, speed, and strain 32
Table 3 - AEDB section data 36 Fig. 10 - Histogram of number of ARGOS location fixes versus time difference
between consecutive .fixes 38 Fig. 11 - Azimuth stereographic projection plots of drift track 40-44 Fig. 12 - AEDB speed and East and North velocity time series 46-50 Fig. 13 - AEDa sphere temperature times series 52
Fig. 14 - PIT battery voltage time series 54-55 Fig. 15 - AEDB sphere strain gauge time series 57-61 Fig. 16 - Speed of AEDB and ice and water temperature time series 63
Fig. 17 - AEDB fluorometry time series 65-66 Fig. 18 - ADCP temperature, tilt, and heading time series 68-71 Fig. 19. ADCP battery voltage and transmit current time series 73-76
Fig. 20 - ADCP echo amplitude data for beam 1 78-81 Fig. 21 - ADCP echo amplitude data for beam 2 83-86 Fig. 22 - ADCP echo amplitude data for beam 3 88-91 Fig. 23 - ADCP echo amplitude data for beam 4 93-96 Fig. 24- ADCP absolute velocity time series for the east direction 98-101 Fig. 25- ADCP absolute velocity time series for the north direction 103-106 Fig. 26 - ADCP velocity time series with depth average removed, east direction 1 08-111
Fig. 27 - ADCP velocity time series with depth average removed, north direction
113-116
Fig. 28 - ADCP vertical velocity time series 118-122
ii
Acknowledgements Without valuable advice and assistance from a large number of engineers and scientists at the Woods Hole Oceanographic Institution, the AEDB project would never have been completed. These individuals include K. W. Dohert who designed the surface buoy, A. Gordon who coordinated the construction of the buoy, P. Clay and S. Manganini who designed and helped construct the
underwater array, E. Mellnger who assisted in the design of the satellte communication system for the AEDB, Dr. A. J. Wiliams who provided underwater electronic loggers, Dr. R. Koehler and A. Sharp who designed and assisted in the installation of the strain gauge circuitry in the interior of the sphere, K. von der Heydt who provided us with valuable advice on the expected ice conditions in the Transpolar Drift, and E. Evans who assisted with the collection of the satellte data. We thank all our colleagues cited above. We are grateful for our research partners at the U. S. Cold Regions Research and Engineering Laboratory, Hanover, New Hampshire, in particular Dr. D. Perovich, Dr. W. B. Tucker II, and Dr. J. Govoni whose help and advice were most crucial for our successful field operation. They furnished a large
diameter pressurized hot water auger, making it possible to dril a large diameter hole through the multi-year ice with unprecedented efficiency. Without the FS Polarstem, which successfully brought the AEDB as far
north as 8So N by breaking up the ice-filed Arctic Ocean, this program would never have gotten off the ground. We thank Dr. Jörn Thiede, Chief Scientist of
the Arkis IV Expedition, Leg 3, cruise coordinator Dr. S. Pfirman, logistics officer R. A. Krause, and the Master, officers, and crew of the Polarstem and the Alfred Wegener Institute of Polar and Marine Research. Co-author R. Krishfield, AEDS project coordinator, extends his gratitude to the many scientists and crew on
board the Polarstem who volunteered to assist him in deploying the AEDB on the pack ice. The most crucial help was provided by the Marine Research Institute, Reykjavik. Dr. J. Olafsson coordinated the recovery operation of the AEDB with
the cooperation of the Icelandic Coast Guard aircraft. MRI dispatched the R/S Ami Fridriksson with Chief Scientist Dr. S. Kristmansson to cooperate with R. Krishfield in pursuing the recovery of the AEDB under rough sea conditions. Without the skill and enthusiasm of the captain, crew and scientists of MRI, the AEDB could not have been recovered. Our most sincere gratitude is dedicated
to them.
iii
We received a great deal of encouragement and support from international colleagues before, during, and after the experiment; in particular, Dr. H. Hoeber, Meteorological Institute, University of Hamburg, who provided us with wind and temperature data from his drifting buoy. We thank Dr. P. Wadhams, Scott Polar Research Institute, Cambridge, Dr. K-P. Koltermann, German Hydrographic Institute, Hamburg, and Dr. E. Hartwig, ONR, Arlington for valuable
encouragement and suggestions. This study was supported by the Office of Naval Research, Code 1125AR, Arlington, VA, under the grant N00014-87, 88, 89-J-1288. It was Dr. G. L.
Johnson who encouraged pursuit of this ambitious program in 1987 and guided us to the successful completion. Dr. T. B. Curtin, who succeeded as manager of ONR's Arctic Programs after Dr. Johnson, also gave us very valuable advice and participated in the interpretation of all phases of the physical oceanographic data
gathered by the AEDB. We are most grateful to these two colleagues. This report is dedicated to the two founding fathers of the science of the Transpolar Drift, Fridtjof Nansen and Ivan Papanin. Their courage and insight inspired modern Arctic oceanography, 100 and 50 years ago, respectively.
, . ~J ~ L
f
iv
The Arctic Environmental Drifting Buoy (AEDB) Report of Field Operations and Results: August, 1987 - April 1988 by Susumu Honjo, Richard Krishfield, Albert Plueddemann
Woods Hole Oceanographic Institution Woods Hole, Massachusetts 02543 January 1990
Abstract There are strong reasons to gather data on polar oceanography and climatology
in real time using fully automated, unattended instrumentation systems for long periods; partcularly during the inaccessible winter months when moving ice is extremely hazardous. We deployed an Arctic Environmental Drifting Buoy (AEDB) on 4 August 1987 at 8S" 7' N, 22' 3' E off of the FS Polarstem on a large 3.7 m thick ice island. The AEDB consisted of 2 major components: a 147 cm diameter surface float housing ARGOS transmitters and a data logger for ice-profilng thermistors, and a 125 m long mooring line attached to the sphere and fed through a 1 m diameter ice
hole. Along the mooring were deployed 2 fluorometers, conductivity and temperature loggers, an Acoustic Doppler Current Profiler (ADCP), a current meter, and a timeseries sediment trap/micro-filter pump/transmissometer unit. The AEDB proceeded southwesterly with the Transpolar Drift at an average speed of 15.3 km/day, with a maximum speed of 88.8 km/day. On 2 January 1988, the AEDB dropped into the water while passing through the Fram Strait and for the remaining drift period was either free-floating on the water surface or underneath the sea ice. Throughout this
period, the transmitters onboard successfully transmitted position, temperature, and strain ~aused by ice on the sphere. Although the sediment trap package was lost
during the drift, valuable data was collected by the other instruments throughout the experiment. The ice thermistor data was used to determine oceanic heat flux, while
continuous ADCP observations over the Yermak Plateau provided a wealth of information for understanding internal waves in the ice-covered ocean. The buoy was recovered by the Icelandic ship R/S Ami Fridriksson on 15 April 1988 at S5" 17' N, 31" 38' W, off southeastern Greenland, completing 3,900 km of drift in 255 days. We are
in the process of constructing the next automated stations which are planned for deployment in both the north and south polar regions in 1991-92.
i
1. Introduction Environmental investigation of the Arctic has never been more important
than it is now with respect to global change and many aspects of world security. Strong justification for further studying the oceanography of Arctic sea ice includes the following reasons: First, sea ice insulates the latent heat of the water, thus the properties of the Arctic sea in the packed and mixed ice zone decisively influence the present climate dynamics of the northern hemisphere. Both the extent and the thickness of the polar sea ice covers are sensitive to the transfer of heat from the ocean to the underside of the ice (Untersteiner, 1986; Maykut, 1982). Second, the Arctic is the precursor of global environmental
change because of the unique characteristics of the physical phases of water
(Andrews, 1988). Scientific observation of sea ice provides us with the first signs of long-range climatic change caused by anthropogenetic forcing, such as the green house effect and the reduction of reverine discharge in the Arctic basin. Among many important ice-covered ocean areas of the Arctic, the Transpolar Drift has gathered the most attention from multidisciplinary studies. Essentially, the ice formed in the Arctic basin flows in a clockwise gyre in the northwestern basin and straight southward through the pole, then exits the Arctic
Ocean through the Fram Strait, and continues to drift along the east coast of Greenland while dissipating volume by mixing southern Norwegian and Icelandic Currents. This linear southward portion of the drift, from offshore East Siberia Island to its extinction southeast of Greenland, is called the Transpolar Drift
(Figure 1). The Transpolar Drift is the largest single drift of sea ice (0.2 Sverdrups at the Fram Strait; Wadhams, 1986), which provides an enormous negative heat flux to the Nordic Seas and also to the North Atlantic Ocean. In addition to its importance in relation to its physical and climatologicål setting, the Transpolar Drift appears to contribute an important role in the
biogeochemical cycles of the North Atlantic. For example, recent biogeochemical studies of ocean stations in the extreme north and south of the Atlantic Ocean have revealed many conspicuous differences in their ocean processes of carbon
cycling (e.'g. Honjo, 1990). First, the magnitude of particulated carbon (and nitrogen) brought into the Greenland and Norwegian Seas is several times greater than the amount brought into their Antarctic counterpart, the central
Weddell Sea. Second, against expectations, the Nordic Seas comprise a "carbonate ocean" where the calcium carbonate flux exceeds that of biogenic silica, while the pelagic Southern Ocean is a "silica ocean" where a very small 2
Figure 1
General ice flow pattern in the Arctic Basin (Gorshkov, 1983)
150° W
180°
1500E
120°
120°
900E
60°
60°
300W
0°
300E
3
amount of calcium carbonate is produced by primary producers. Third, a relatively high carbon and nitrogen flux, close to the annual average, is maintained in the Fram Strait-Greenland Sea area during mid-winter. In contrast, under the pelagic Southern Ocean ice sheet phytoplankton production decreases to almost zero during the austral winter. Explanations for these biogeochemical characteristics of the Transpolar Drift area are not readily available. One hypothesis is that the Transpolar Drift is more correctly defined as a conduit system which transports the Arctic river discharge through the Arctic .mediterranean, thus making the Fram Strait the true combined estuary of all Arctic-basin rivers. Consequently, the Drift carries compounds which strongly influence the biogeochemical setting of the southern area of the Drift and the Nordic Seas
significant river elements and
(Honjo, 1990).
Our long-term objective is to clarify the global role of the sea ice that moves through the Arctic Basin and overflows into the northern Atlantic Ocean by depicting its physical, energetic and biogeochemical characteristics; particularly those characteristics of the southern Transpolar Drift, where the melting process is more significant than new ice formation. In pursuit of this objective, a number of significant contributions made in the last decade can be cited, including the modeling of Arctic ice motion (e.g., Hibler and Walsh, 1982), glaciology (e.g., Weeks and Ackely, 1982), marine chemistry (e.g., Öslund and Hut, 1984: Jones Ice Zone studies (many international MIZEX related publications: Johannessen et aI., 1983), and particle flux/biogeochemistry (e.g.,
et aI., 1990), the Marginal
"
Honjo, 1990).
From a" more historical perspective, Transpolar Drift research has
developed through a number of glorious benchmarks of adventure and scientific accomplishment. It was the ingenious idea of Fridtjof Nansen to freeze a . specially-built ship, the Fram, into the ice of the East Siberian Sea and allow it to drift; expecting that the current would bring the ship to the North Pole. Nansen was convinced that the wind-driven polar current was the agent responsible for transporting the wreckage of the Jeannett from the East Siberian Sea through the passage between Svalbard and Greenland; this current is now known as the
Transpolar Drift. This Norwegian North Pole expedition, which travelled with the pack ice from 1893 to 1896 (Nansen, 1897), not only returned with a wealth of information about Arctic sea ice in the basin, but also strongly impressed polar researchers with the value of long-term scientific camp-research.
4
In 1937, Ivan Papanin and his colleagues set up a scientific station on an ice floe which drifted south through the Fram Strait and along the west coast of
Greenland. This expedition acquired an enormous volume of high-quality sea ice (as well as oceanographic) data which spanned all disciplines and established the foundation of Transpolar Drift research practiced today. Since then, more than 35 long-term drifting ice camp expeditions have been attempted all over the ice covered Arctic Ocean, including Alpha (Canada), long-standing "North Pole"
expeditions (Soviet), and the most recent Coordinated Eastern Arctic Research Experiment (CEAREX).
The Soviets began to deploy unmanned radio stations to understand the variabilty of the trajectories of the Transpolar Drift in 1953 and maintained the program into the 1960s (the Drifting Automatic Radio-Meteorological Station program). However, as Dr. R. Colony noted, very little data from these
experiments has been published (Colony, 1990). Since the late 1970's, the Arctic Buoy Program (Untersteiner and Thorndike, 1982) has simultaneously placed up to 20 automated buoys over the entire Arctic Basin; each of which was linked to a land laboratory through the ARGOS satellte. These air-dropped buoys have collected data on ice motion, surface atmospheric pressure, and surface temperatures for more than 100 station-years up to the present (Figure 2, Thorndike and Colony, 1980). Using similar technology, the Norwegian programs also contributed to an understanding of the ice motion, particularly in the southern Arctic area (Vinje and Finnekasa, 1986). These data are the foundation of the modern observational understanding of sea ice motion in the Arctic Basin. The highly successful Arctic Buoy Program mentioned above should be continued in ordedo cover yet unexplored areas of the Arctic and to gather more information on the inter- and intra-seasonal variabilties of ice movement in the Arctic Ocean and elsewhere. However, we realize that the Arctic Buoy Program is stil only a small fraction of what is required in Arctic environmental research for understanding its critical role in the changing earth. In particular, we need more year-round observational oceanographic information from underneath the sea ice
(Aagaard, 1989). Specific examples of what is required are measurements of the variability of temperature, salinity, primary productivity, and other critical criteria in
the upper oceans with reference to the thermal properties of sea ice and its thickness, thermal structure and its variability of holocline water, details of the current structure and its relation to pack-ice movements. Time-series observations of particle fluxes and associated biogeochemical information are 5
Figure 2
Drifts of the buoys in the Arctic Ocean Buoy Network for 1979 (Thorndike and Colony, 1980)
150.
180'
150'
February 1, 1979 - January 1, 1980
90.
~ -~t 30.W
b
~~ ,
d~
'ô
O.
30.E
6
vital to understand the biogeochemical processes in the Arctic Ocean and to make paleoceanography more useful for the prediction of environmental changes
taking place in the Northern Hemisphere. Frequent, synchronous measurements of a variety of parameters must be made using tightly controlled coherent methods, so that an investigator can cross reference between multifaceted data sets in order to gain a more comprehensive
understanding of the environment. The advancement of recent sensor technology, in-situ data processing, and satellte data transmission led us to design an automated, extremely durable, self-sustaining, multi-sensor environmental data collecting station which could function independently for more than one year. We designed and produced a prototype model of an ice-tethered mooring array, called an Arctic Environmental Drifting Buoy (or AEDB), with the support of the Office of Naval Research, Arlington, Virginia in 1987. A detailed description and review of the design of the AEDB, its procedure of deployment and recovery, and the scientific results from this prototype experiment are presented in this technical report. The AEDB experiment was primarily designed to study the feasibilty of developing and operating a multi-sensor automated station which could be deployed as an ice-tethered mooring system, but also survive as a surface float when released into the water. In particular, the buoy had to be able to withstand extremely harsh conditions while it was in a mixed ice zone. The survivability of any conventionally designed buoy with a long and heavy underwater mooring array is considered to be very slim under dynamic mixed ice zone conditions where ice floes crush and pile up on any floating object. The prototype automated station consisted of an ice-ocean surface float and a 125 m taut line mooring array with many sensors. The spherical buoy was
147 cm in diameter and served as the surface flotation device. On the outside of this buoy, two pancake antennae for satellte transmission were mounted. Inside, dual ARGOS communication electronics (Platform Transmit Terminals) and an electronic logger for ice profiling thermistor chains were housed in a watertight
cylinder. Against the inner steel skin of the buoy, 6 thermistors and 8 strain gauges were attached. The skin itself was galvanized, 5 mm thick, soft steel which recorded the major crushing events as dents, while measurements from
the strain gauges were simultaneously broadcast. Eight-word data packages from each PTT, including pressure on the sphere, temperature, and operating voltage, were transmitted via the ARGOS system and received at the Woods Hole Oceanographic Institution approximately 20 times a day. The remaining 7
"
L L
t
space in the sphere was filled with non-permeable closed-cell polyurethane foam.
The array was joined to the bottom of the sphere via a gimbal mechanism. Along the 125 m of taut line, 15 sensors, including an Acoustic Doppler Current Profiler, conductivity and fluoresence loggers, and a sediment trap/micro-filter
pump package with transmissometer, were deployed as ilustrated in Figure 3. In this prototype station, the technology to transfer the signals from the underwater
sensor packages to the satellte transmitters was not established. (This design has recently been completed and wil be applied to the 1991 IOEB experiment.)
Therefore, four large capacity, solid-state electronic loggers were deployed at 3 depths. A 300 kg anchor at the bottom of the line completed the array. The AEDB was settled on a multi-year ice floe with an estimated size of several square kilometers at 86° 7' N, 22° 3' E, on August 4, 1987 off of the FS Polarstem, Alfred Wegener Institute of Polar and Marine Research, Bremerhaven, FRG, Dr. Jörn Thiede, Chief Scientist. After drifting southward with the Transpolar Drift for approximately 3,900 km through the Fram Strait and along the east coast of Greenland, the AEDB was recovered on April
15, 1988 at
6So 17' N, 31° 38' W (west of Iceland) by the RlS Ami Fridriksson, Marine Research Institute, Reykjavik, Iceland.
We were successful in recovering most of the underwater sensors except for the sediment trap-transmissometer package which was lost during the drift. As seen in this report, the quality of much of the retrieved data from the scientific sensors, particularly drift speed/direction and subsurface current profiles, is excellent and usefuL. Publication of scientific results of the 1987-88 AEDB experiment has already begun (e.g., Perovich et ai', 1989). In conclusion, we have found that an automated ice-ocean observation station,' such as an AEDB, can be deployed in an energetic environment such as
the Transpolar Drift and will retrieve a large amount of useful high quality data from many sophisticated sensors; although we found that some aspects of the individual data collection devices need improvement. It is obvious that automated ice-ocean observation systems are worthwhile in overcoming the extremely adverse conditions of polar oceans; especially during the winter. Recent technology indicates that the quality and quantity of data acquired by
an
automated station can exceed that of a manned station, which tends to be
considerably riskier and more expensive. Still, an automated station is not feasible for some types of research, such as bottom coring. While it was once impossible to do synchronous measurements of critical parameters in vastly
remote areas like the northern and southern Arctic, or even in the Antarctic. 8
Ocean, now it is technically feasible. Based upon the experience from the successful (prototype) AEDB experiment, we have designed and are in the process of constructing a more sophisticated version of an automated polar ice-ocean research station: the IceOcean Environmental Buoy (IOEB). The major difference in an IOEB from an AEDB is that the majority of measured signals from sensors, including those from
an ADCP, wil be transmitted via satellte. Using a new material for the surface float, based on the results from the AEDB's strain gauge information, the IOEB is
far more lightweight and therefore portable by helicopter. In 1991, a group of international scientists plans to deploy a number of IOEBs, not only in the Transpolar Drift (USA), but also in the northern Arctic's Canadian Basin (Japan), as well as in the Southern Ocean's Weddell Sea (UK-Norway). Instant, direct and synchronized comparisons of those extremely remote but ordinarily sea icecovered areas should provide us with more valuable information needed to understand the polar environment and should enable us to produce more realistic
prediction models.
9
2. Description of the AEDB 8. Overview The AEDB had two major components: a 5-foot diameter steel surface float and a mooring line of self-contained oceanographic instruments extending
through a 1 m diameter icehole (Fig. 3). The foam-filled surface sphere housed the ARGOS telemetry systems required for determining the location of the buoy and provided triple the buoyancy required to maintain the 500 kg of mooring
instrumentation. The surface float was constructed from a 147 cm O.D. Navy surplus steel
sphere, of the type used during World War II to cordon off harborways. The thickness of the steel skin varied between 5 and 7 mm, amounting to an air weight of 300 kg when empty. The original surface had attachment points at either pole and a single fil/vent plug. At WHat, the sphere was cut open and a 53 cm diameter cylindrical tube segment was added, providing interior access
from the top. Fifty kg of lead was added to the floor to increase the vertical stabilty of the float. Strain and temperature sensors were positioned on the inside wall of the sphere, while on the outer surface, two patch antenna mounts were fixed at 34' angles from the verticaL. Accessible from the top of the sphere, a cylindrical watertight aluminum
compartment housed a rack of electronics for ARGOS telemetry, sensor conditioning, and data logging operations. The temperature and strain sensors mounted on the inside wall of the sphere were interrogated by the two ARGOS
transmitters inside the housing'. Two thermistor chains installed in the ice surrounding the buoy were attached to the sphere at a watertight bulkhead along its equator. Linking the thermistor chain connector on the sphere with the bulkhead on the inner housing lid was a 36-wire pressure resistant extension cable. Watertight bulkhead connectors and cables were used between the . external devices and the inner housing lid to ensure isolation from external moisture at pressures up to 150 PSi. With all the cables and the housing installed, the space between the inner package and outer steel shell was filed with a cellular insulating foam to provide backup buoyancy if the steel
shell
cracked under ice pressure. Flat patch antennas were used on the AEDB to physically transmit the
signals to the ARGOS satellte. These durable antennas do not protrude above the surface of the sphere which makes them optimal for a hostie Arctic environment. Furthermore, each antenna radiates a 180' pattern which, between 10
Arctic Environmental Drifting Buoy ,. DSI Patch Antenna PRL PTT Temperature and Strain Gauge Strain and Temperature Interface
Figure 3
5' Diameter Steel Sphere
Battery Campbell Data Logger MUX and Memory I
Ice Thickness
3.7 m 2
-
Universal Bale/Joint
Reinforcement Hole Diameter = 1 m
Chains I Ice-Thermistor
5 m 314" Chain
5 m 5/8" Chain
-6m- "1 1 I
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9 m 112" Chain
~I ~I
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18 m 3/8" Wire Rope 75 m 314" Nylon
-120 m2m 1/2" Chain
-122 m_
2m 1/2" Chain
11
the two units, makes signals to the satellte visible from virtally any angle the sphere may be at in relation to verticaL.
The mooring line which extended through the ice to a depth of 125 m
below the surface of the water was deployed with the following instrumentation: -two fluorometer packages; -a temperature thermistor chain and micrologger;
-an Acoustic Doppler Current Profiler (ADCP);
-an electromagnetically induced current meter; -an instrument package consisting of a time-series sediment trap, a time-series water casting/filtration pump, and a precision transmissometer with data logger; -two conductivity/temperature (CIT recorders.
All instruments were synchronized to take readings at the beginning of the hour, respective to their individual scanning intervals. A summary of the deployed
operating parameters and specifications is given in Table 1. A detailed discussion of the functions and placements of each of these instruments on the mooring line follows. The two major concerns in the design of the mooring system of the AEDB were the survivabilty of the buoy in the ice, and the survivabilty of the mooring line once the buoy is in the open ocean. In the ice, the surface sphere has to withstand destruction by collding ice floes, as well as damage by aggressive polar bears or other outside forces. Out of the ice, the buoy must remain afloat in whatever sea conditions exist, in order to be located and recovered. Furthermore, the mooring line.must not be ripped from the sphere in either
situation,else the majority of the internally recorded or collected scientific
information wil be lost. Three sizes of galvanized chain (1/2", 518", and 3/4"), 3/8" wire rope, and
3/4" nylon connected the instruments, or instrument frames together. While the shallow fluorometer package was attached to the mooring on a stainless steel strongback, the deeper fluorometer package was mounted in an electropolished stainless steel frame with the ADCP and one CIT unit. These units were mounted together to eliminate interference in front of the downward facing sensors of the ADCP. For the same reason, the fluorometer located below this package was mounted in an in-line stainless steel cage to prevent it from protruding out from the mooring line. The 84 current meter was located in-line, while the sediment trap, pump, and transmissometer were mounted with the
second CIT unit in a galvanized aluminum frame. At the end of the line hung a 12
W
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c:Ot07S/m
(.001 VI
+1- 0.5%
t: -5 to +35 C
(0 to 5 VI
o to 100 %
dB
-MåY-8f -
- --
7 May, ()5 C
o.OOj?m/mo 0 to 6 S/m
0.01 C/6 m -1 to 31 C
- - - - - 19 Jun
(+1- .5 mV) _ 0.:4!5_ V_ _
+I- 0.4% ~ 095%
_._ _ _ _ _
2.5
+1- 0.2 C
2deg .005 V
+1- 1 cm/s 0.5 deg
0.1 C
0.2 cmlB
0.01 C
to 6 Slm -0.0001 - - - Slm - r O'~/~/mo - - - - ~0-19.iñ - .
0.001 C 0.01 CI8 m -1 to 31 C
8 m bins
16 Jun
(+1- .5 mY) 0 to 5 V
+1- .015 I 0 to 5 mlgn
.25 mV (.05% FSRI
+1-.5 C
2601 bottles _ _ _ _ _ _ .. _ _ _ _ _._ _ _
days
3031 memo!)
15:00 year
28 Jul 11 hour 11 I ballery I -5 to +35 C
year c: 0 to 7 S1m
1 hour I 1 I ballery I t: -5 10 +35 C
collecls 13, 250 ml boiiies of 4 Aug j 20
- 10-bll tem erature and de th
- 8-bll reference vollage
N & E current vecors
- 12-blt Earth referenced
records:
recrds In 96 Kb RAM
conductlvily In 64 Kb RAM .
frequencies of temperature and ~~.~~I
reeOds - 4:"byeŠ óf WŠO - - - -1- - - -
on 8 Mb tape cartride
- echo amplhude, percent good. and stalus
ma. depth
days 1810338 m
(.00 Y)
0.03 mlgn
(.001 Y)
0.03 mlgn
33.3 mlcV
150 ml"r
0.25 V
0.3C
Resolution Accuracy Calibration
Specifications
~ ;I:I~~ ~;e; ~;o - - ~; - 1.0 cmse
days . (0 to 5 VI
1 hour 1341 fmemo~ 0.05 to 5 mlgll
days I (0 to 5 VI
1 hour I 341 I memory 0.05 to 5 mlgI
18 :00 days
sample avg. In 16 Kb RA .
- tilt
strain gauges: +1- 200 ml"r
11to 18.75 V
ballery vohage:
-50 to +26.5 C
baiieryltemperature:
26 Jut 18 hour 13421 memory +1- 0.5 V
~eploylng
prior to man
2 weeks 160 sec 118
Started Interval Du. Umiter Ranae
30 Jul records12-blt vollage of 32 ~13'00
records12-bll vollage of 32 sample avg. In 18 Kb RA
RAM
In 102 Kb tolal solid-stale
resistance values
- 35, 12-bit thermistor
- dale and time of meauramnt
records:
- 4 slraln gauge measurements
- 3 surface temperatures - ballery voltage of unh
words conslsUng of:
each transmits eight 8-blt
Information
Deployment Parameters
days _L______. rr ~---------270-IIters _ _ _ _ ëoÌeeiš 2Õ,-47 iñiñ diameier; 4Aug-15Micro-Filler Pump .~7_ m~c_p~r~ ~!.i:Ð~ f~e~s _ _ ~~O~ _ _d!y! days -l_______.. -----
120 m I InterOceans 54 Current Meter
26 m I Sea Dala TR-3 Temperalure Mlcrologger
16 m
6m
Ice
-- - CRREL iCe -ThermlstÓr Cháiná - - - - - - - - - - - - -
SMM Storage Module
with: AM32 MulUplexer
Campbell 21 X Data logger
BlH strain gauges Wllh praampllfler boards
YSI temperature thermistors
each whh: DSI 401.650 Mhz Palch Antenna
Inside I Polar Research lab Pial
sphere l841
Depth Instrument
Equipment List
-L
(j
;t C"
railroad wheel, providing ballast for the mooring. Throughout the line, no link was rated at less than 5,000 kg maximum load. Anticipating that the buoy would spend a portion of its time in the open ocean, a 75 m length of nylon and 350 kg depressor weight at the bottom of the mooring line was incorporated to allow the sediment trap to be dynamically
decoupled from the sphere in moderately rough seas. The nylon was to reduce the sea anchor effect of the sediment trap, while the weight would maintain a positive mooring line tension in most fair weather sea conditions. Furthermore, a steel universal/bale joint attached the mooring line to the sphere with the purpose of reducing friction at that critical juncture.
b. ARGOS Platform Transmit Terminals (PITs) The Polar Research Laboratory PTTs each transmitted eight words of
sensor information via ARGOS satellte to ground stations where the position of the buoy was determined by the Doppler effect on receive frequencies. The buoy was monitored daily for its position in (or out of) the sea ice. While this information was essential for recovery, it also provided ice drift vectors which have been incorporated into the ADCP current measurements made below the
surface. Each PTT transmitted three temperature readings from temperature sensors positioned along vertical lines on opposite sides of the sphere (Fig. 4). Each set had one sensor mounted on the equator, and one near either pole of
the sphere. The intention was to analyze the temperature differences at six locations of the float and determine characteristics of the environment surrounding the sphere. Due to the thermal conduction of the steel shell and inaccuracy of the measurements, however, the differences between the separate sensors were insignificant. Strain gauges mounted along the sphere's equator were used to indicate the presence of ice pressure surrounding the buoy, while strain gauges mounted on the floor of the sphere were intended to observe excessive force in the direction of the mooring line (Fig. 4). Each PTT transmitted data from four strain gauges representing one half of the float, divided vertically. Altogether, each ARGOS transmission contained 3 words of temperature, followed by the lithium battery voltage of the PTT unit, followed by 4 strain gauge readings. For positioning purposes, the PTTs transmitted a new message every 14
Figure 4
Sensor Positioning on Buoy Sphere
Arctic Environmental Drifting Buoy T2 SA2
T2Y
o
(SBI)
SDI
SC2
(SB2)
SD2
PTT 8440 transmits: Tl Y, T2Y, T3Y, battery voltage, SC1, SC2, SD1, SD2 PI 8441 transmits: TlR, T2R, T3R, battery voltage, SAl, SA2, SB1, SB2
1S
sixty seconds. Due to the path of the ARGOS satelltes around the Earth, however, data was only acquired from the AEDB float a maximum number of 28 ten-minute periods per day. The wiring diagram for the PTT system is shown in Figure 5. Temperature requirements of the Arctic winter dictated that the PTTs be provided with lithium battery power to ensure an operating range down to -40 .C, and a duration of at least 16 months. Two completely redundant ARGOS systems were incorporated in the event that one should faiL.
c. Temperature and Conductivity Measurements The AEDB was outfitted with a total of 48 thermistors in order to provide a temperature profile of the air, ice, and upper 122 m of water with respect to space and time (Fig. 6). The ice thermistor chains are described in detail the next section. Conductivity was recorded along with temperature at two locations (15 and 122 m), with the intention of providing a two point salinity curve below the ice floe.
The six temperature sensors mounted inside the surface sphere are influenced by the large time constant of the sphere and resolve only 0.3 .C. The sphere temperature provides a rough indication of the temperature of the surrounding environment, but is not exactly the air temperature. Only this information was transmitted in real-time; all other temperature data was internally recorded with varying degrees of success.
The Campbell data logger was configured to acquire high resolution data from the 36 ice thermistors, four times each day. Approximately 12 of these sensors extended below the ice floe to a depth of 1.8 m into the seawater. The Sea Data Micrologger was incorporated with four temperature thermistors attached to the mooring line at depths 6, 16, 21, and 26 m below the icefloe. These depths were chosen with respect to the fluorometer packages in order to monitor the changing temperature maximum with respect to the fluorescence readings. The memory capacity of the micrologger is such that it
could record data for over 400 days, although alkaline battery life limits the acquisition period to one year. At 15 and 122 m below the ice floe, Sea-Bird SeaCats were configured
to record high resolution temperature and conductivity. Every hour, the SeaCats would store precision readings of the temperature (resolution = 0.001 .C) and
16
,
-
.1 h
ai ::
.. 0'0
. .:
o as m CD
-i '0
~
(! "s U) a:
3 ' ::
I'
10
~ii
3
~~.
II i
i
Sii2
i- Sii 1
10ii
Shield
\
1\\
Ii.
X
+5 Ref
A22 m t2..0..'" ,.. nn¡1"l!
AllCl
Strin
Te:p (
Te:p (
Temp
21
20
ii
27 23
2
ci
1!
c:
.Ë
Qj
.!
uCD
C .. a:
I'
43
37
13
is
46
5
4
JIB
IlB
'46
is
13
43
37
I'
ci
..
ïã
c:
.Ë
èD
8
.!
~
0
JlA
21
20
22
17 23
2
4
5
JZA
T3A TIB
~li&1 Sil TI
T2
Sii Ti TiA
+5 Ref
Shield
TIB
¥fl1
+5 Ref
Shield
--- --In 7
In ,
J3
-Iii
-112
,
II;
rl l
,14
II i I 3
2
i J i,
2 7
n
I
I
Ballery Packs
lithium
Platform Transmit Termnal Sensor Wiring Diagram
I
i
-- -- -- --
Patch Antenna
401.650 MHz
01
(0
iI ~. c:
Figure 6
Ice
Thermistor Chains AEB
Ice
Thermistor Chains 1(25501
15 m . Seacat Sea Data
2 (25511
3 (25521
4 124531
5 124541
6 (24551
7 (24561
8 (24571
Temperature and
9 124581
10 (24591
Conductivity Sensors
II (2461 13 (24621 12 (24611
25 14 (24631 "
15 (2464)
10
5
16 17 18 19 20
5
~~ imy:
5 5 5 5 5
24 2413
5
5 5 5
Ice Thickness
.. 3.7 m
5
5 5
.c = temperature
(24651 (2466) . (24671 (24681 (24691
Z5 (24741
~~ im~: 28 29 30 31
(24171 (24181 (2419) (24801
10 32 (24811
10 35 (24821
.. .. conductivity and
temperature
25 34 (24831
100
35 (24841
S4 - 120 m
122 m - Seacat
18
conductivity (resolution = 0.0001 S/m) of the surrounding seawater. The conductivity sensor was provided with anti-fouling devices to prevent drifting of the sensor over the duration of the buoy deployment. Alkaline batteries are sufficient to power these data loggers for approximately one year.
d. Ice Thermistor Chains The U.S. Gold Regions Research and Engineering Laboratory (CRREL) provided the AEDB with two ice thermistor chains which were installed in the 3.7 m ice surrounding the sphere (Fig. 6). The data from these was stored inside the
sphere in the Campbell electronics package. By measuring ice temperatures, the heat flux between the ocean and the sea ice can be determined from the
changing ice thickness. One string had twelve thermistors extending from the surface of the ice to a depth of 3 m. Half a meter below the surface thermistor, the remaining
eleven thermistors were spaced at 25 cm intervals. Silcon cement bonded the thermistor wires to a sectioned wooden doweL.
. Placed in the same four inch ice hole, the second string consisted of 23 thermistors, with 5 cm spacing between those surrounding the bottom of the ice floe. The deepest two thermistors hung below the string's dowel framework at
approximately 75 and 175 cm distance from the bottom of the floe. The two length of 4.5 m. The plastic attachment sleeve of the connector to the sphere was designed to separate when the icefloe breakup pulled the thermistor chains away from the float; ensuring that previously recorded data would not be affected when this occurred. The combination of a Campbell 32 channel Multiplexer and 21 X Data Logger was used to interrogate the thermistors and feed the calculated strings overlap for a total
resistance value to the 64 kbyte Storage Module every 6 hours (Fig. 7). The computations performed in the 21 X use 4 bytes for floating point arithmetic. The storage resolution decreases as the value increases, but the thermistors exhibit logarithmic increase in impedance with increasing temperature over the range
-40 to +40 .C. The thermistors were calibrated at three temperatures at CRREL to provide an accuracy of 0.01 .C. At the selected sampling rate, the storage module would be filled in 215
days. The 21 X contains enough memory to collect an additional 127 days of information, for a maximum of 342 days of data collection. The 21 X provided
19
Figure 7
Wiring Diagram for Campbell Data Logger
Thermistors
21X
AM 32
1
2 COM H
H
0 z:: :: 0 0 a:
COM L
L
RE
(N
Q ~ :: a. 5 ~ a. :: ~
CLK
H
w
4
F=
.
a: u.
.
29 30
:: a:
en
3
.
31
N
(W
32
C)
-i
1
2
L
+12 V
(N
G\
1
33 34 35
i-1.000
K-
(N
-1.004 K-
(N 2A
:; ~
:; il
-- ---
--
.983 IE .994 IE
2
-
EXC
3
4 1
2CONT +12 V
(N
20
power from fused lithium "D" cells to itself, the multiplexer and the storage 9.5 Ah of power, which is only two thirds of the temperature derated capacity of the cells. The module. For 342 days of operation, the system would require
storage module had a separate backup lithium battery to retain its information should the main power to the data logger become depleted.
e. Fluorometer Packages
Information on the variabilty of phytoplankton pigments under and near the sea ice wil provide a key to understanding the productivity of polar and high latitude ocean environments. Two high-sensitivity fluorometers with data storage modules were incorporated on the AEDB to monitor this activity.
The Sea Tech fluorometers are designed for in-situ measurement of fluorescence in seawater. Excitation is accomplished by the emission of bright blue light from a Xenon flash lamp. The optical components have been selected to be almost completely insensitive to ambient light below the water surface, while optimizing emission detection of chlorophyll a. At the high sensitivity setting, the fluorometer detects concentration levels from 0.05 to as much as 5 ug/I with a resolution on the order of 0.03 ug/1. The signal gain was set to high sensitivity and the amplifier time constant to 1 s. The fluorometer must be both powered and controlled externally. Separate OIS Data Loggers were used to control, digitize, average, and sto're the
output from the fluorometers. Each logger has programmable sampling rate, delayed starting, sensor warmup time, and sample averaging. The units communicates with external terminals via RS-232 serial protocol. Duri.ng this project an HP 85 Personal Computer was used for initialization and a Toshiba 1100 laptop for data retrievaL.
The sampling rate of the logger is selectable from 20 s to 85 min. At the sampling period, power is applied to the external sensor; in this case, the
fluorometer. After an appropriate number of half seconds (determined by the setup of the warmup variable), the first measurement is made. The 0 to 5 V analog input is converted by successive approximation to a 12-bit value between o and 4095. Every next tenth of a second a 'new value is calculated until the
selected number of samples to be averaged is acquired. The averaged value is then stored in 2 bytes of 16 kbytes total RAM. Up to 8,192 measurements may thus be stored before the memory of the unit is exhausted. With a one hour
21
interval between readings, the memory of the data logger would fil in 341 days at which time no more information wil be recorded. A backup battery ensured that no data would be destroyed should the main battery pack have been depleted. The fluorometer draws approximately 1 amp of current with each flash. The battery capacity to power this unit and the data logger (taking into account temperature degradation at 5 'C) exceeds that provided by conventional NiCad batteries. Consequently, fused lithium power cells had to be used with the fluorometer packages, and a large 10,000 microfarad capacitor provided to prevent passivation of the lithium cells due to the large instantaneous current drawn by the fluorometer when flashing. In this manner the fluorometers were safely provided with over 15 Ah of power; enough to last over one year. The shallow fluorometer was deployed 10m below the sphere, or approximately 6 m below the bottom of the ice floe. The other was deployed 16
m below the ice. Temperature thermistors located at each fluorometer depth, were to be recorded by the Sea Data Micrologger synchronous with the
fluorometer readings.
f. Current Measurements
An Acoustic Doppler Current Profiler (ADCP) manufactured by RD Instruments was deployed in a load cage that also provided the mounting point for the fluorometer package and shallow CIT recorder. The objective of the ADCP deployment was to observe the sub-ice horizontal velocity field as a function of depth and horizontal position (latitude) as the buoy drifted through the Arctic Ocean. The. ADCP uses the Doppler principle to produce a profile of the :f
seawater flow velocity. It operates by transmitting 150 kHz pulses along lines of position defined by the beam patterns of four transducers. Backscattered echoes from plankton and micronekton in the water are received by each transducer with a frequency shift proportional to the relative velocity between the scatterers and the transducer. This frequency shift, or Doppler shift, is converted into a radial velocity for each beam. The instrument was fixed at a depth of 16 m, transducers facing downwards, and configured to record an ensemble of 40 profiles every 30 min. Each profile consisted of 40 eight-meter bins giving a profiling range of 320 m. Since a transmit interval corresponding to 16 m in depth was selected, the 8 m
bins actually oversampled in range by a factor of two. The 40 profiles in each 22
sample were not equally spaced over the half-hour ensemble intervaL. Instead, the instrument was operated in a "burst sampling" mode with the 40 profiles collected at 1 s intervals immediately following the start of the half-hour data collection cycle and averaged together to form the ensemble. The expected accuracy of the horizontal velocity measurements for each ensemble is +1- 1.0
cm/s. The ADCP also contained a thermistor, a flux-gate compass, and a twoaxis tilt meter. The thermistor produces a linear change in resistance with
temperature over the range -5 to 45 .C and is digitized to 0.01 .C resolution. The accuracy of the temperature measurement is 0.10 'C. The calibrated flux-gate compass is accurate to +1- 2. and the tilt measurements are accurate to +1- 1 . up to a 20. threshold. The compass and tilt measurements are used to transform the radial beam velocities measured by the ADCP into earth coordinates. A 60 Mbyte tape drive stores data records consisting of a header block with time, compass, tilt, and thermistor values plus a data block containing the radial beam velocities, the backscattered intensity, and certain data quality
information. Battery life depends principally on the number of pings, the number recorded. of depth cells, the time between ensembles, and the amount of data
For the parameters used here the lithium battery supply of the ADCP is rated to
250 days. Selected ADCP Parameter Settings *
ParameterNalue Description
116 16 m transmit interval J 080 8 m delay after transmit
L 38m bin length
0029 record radial beam velocities, echo amplitude, percent good pings, and status bits P 00040
40 pings per ensemble
Q40
40 bins per ping
R 00300000
30 min between ensembles first ping at 23:00 Z, 07-29-87 1 s between pings
U 0729230000 V 000100
* remaining parameters are set to factory defaults
23
A second current meter was attached to the mooring line 120 m below
the ice bottom. The InterOceans S4 Current Meter hung just above the sediment trap package and was programmed to provide Earth referenced current vectors and low resolution temperature and pressure values at the mouth of the trap. The S4 measures horizontal current by sensing the induction created by the motion of water through a magnetic field created by its flush mounted sensors.
Sampling every hour, the solid state memory of the S4 fils with data 300 days
after deployment.
g. Sediment Trap / Micro-filter Pump / Transmissometer The combination of a time-series oceanic sediment trap, a time-series micro-filter pump, and a precision light transmissometer in a single frame 122 m below the bottom of the ice, were to provide comprehensive particle data along
the track of the buoy. Included in this frame was a second CIT recorder measuring the physical properties of the seawater at this depth. The key component of the sediment trap is a set of sequentially rotating samplers which is driven by a microprocessor-controlled stepping motor. Thirteen 250 ml polyethylene sample bottles are sequentially placed under the
0.5 m2 aperture of the trap; each for a 20 day interval during this experiment
(Appendix C). A spring gasket positively seals each of the bottles from ambient water prior to, and after acquiring its sample. An Epix MPC electronic controller
triggers the rotator and independently records execution of each sampling event. The MPC is programmed using an Epson HX-20 portable computer for the date and time at which each event is to occur. When an' event time is reached, the MPC pulses the rotator stepping motor until the next sample bottle is in place of the last. A microswitch in the stepping motor assembly signals when the rotator has turned the proper distance. Concurrently, the MPC records the time when the event occurred (which should be within seconds of the programmed time) and the number of executed steps (which during proper operation equals 90) in RAM. Upon retrieval, this information verifies proper operation of the rotator/controller, or can be used for analysis of any broken events. A lithium battery provides backup power to sustain the original program and memory should the main battery pack of the MPC be depleted. A similar Epix controller rotates a similar stepping motor on the micro-
filter pump. Twenty.47 micron Metricel filters were to collect suspended particle 24
"
l
¡. . !i
I
samples via the pumping action, which passes approximately 100 ml of seawater
per minute of operation. Every 15 days, the controller was configured to step the pump valve to a blank filter and pump for a maximum of 3 hours, although the pump would cease when the filter clogged with particle materials. Nucleopore filter holders were 'fitted between check valves, to enclose
the filters in a sealed unit. When pumping, these filter holder assemblies introduce only a small friction. When they are removed from the pump, these units act to prevent contamination of the filters from stray particles. Like the sediment trap controller, this MPC is programmable for date and time of each event, but includes other programmable parameters for the pumping action. An event for this system comprises the pumping of a filter followed by 9 steps to the next filter, to await the next event. The pump controller wil discontinue pumping at a programmed time limit, at a minimum flow rate, or when a maximum volume of seawater has passed through the filter. Each of these parameters (like date and time) is determined by the user and relayed to the MPC via an Epson HX-20. The controller determines flow and volume by keeping a running count of the number of revolutions of the pumping motor. Each revolution passes .044 ml of seawater. The pump is current limited to cause it to slow as the filter clogs. Every minute, it checks to see that the pump is not below the minimum flow or above the maximum volume settings. For this experiment, the minimum flow was set at 35 ml/min, and the maximum volume at 14.4 liters (which is the maximum
programmable value). Every 5 min it records the volume that has been pumped during that period. This information is retrievable from the controller, as are the total volume for pumped through each filter, the time of the event, and the number'of steps between each event. A Sea Tech Transmissometer was located just below the sediment trap sample bottles, whose function it was to measure beam transmission in its 25 cm water path. In studying suspendoid dynamics, it has been shown that particle
size, shape and roughness affect beam attenuation. Thus the transmissometer can detect particle concentration changes in clear water of 100 ug/l, but needs samples collected along with its measurements to determine accurate concentrations of particle mass or volume. On the transmissometer, a modulated LED and synchronous detector measures transmission, while remaining insensitive to ambient light. It outputs a linear 0 to 5 volt analog signal corresponding to 0 to 100% transmission in water. The LED light output can decrease slightly over time, requiring calibration of the
25
i
, ¡,
instrument during use. Comparison of a factory measured air value (approximately 95% equivalent transmission) to a present air value corresponds to a proportional change in LED degradation. From this a corrected output
voltage can be computed. The transmissometer was controlled by an OIS Data Logger functionally identical to those used for the fluorometers. As the transmissometer requires
less stabilzing time for its electronics, and outputs less noise than the fluorometers, this data logger was programmed with different parameters than
the others. In this application, the logger provides 3 s of warmup and averages
only 16 samples. There is no impedance mismatching between the transmissometer and logger providing a linear 12-bit conversion through zero. The transmissometer draws less power than the fluorometers, consequently, this
system was powered with alkaline cells and required no capacitor. At an hourly
sampling rate, the memory of the data logger would be filed in 341 days, after which no further sampling would occur.
26
3. Deployment, Drift, and Recovery a. Deployment operation
The AEDB was deployed on 4 August 1987 at the northernmost point
achieved by the FS Polarstern during the third leg of the Arkis IV Expedition. By 1031 UTC, the buoy was resting on four wooden posts at position 86° 7.4' N
latitude, and 22° 3.3' E longitude. Below the sphere lay 3.7 m of sea ice and 3937 m of seawater. Preliminary work was performed the previous day to accelerate the deployment procedure on this day, which took slightly more than two hours to
complete. Leg 3 of the Arktis iV Expedition began in Tromso, Norway on 4 July 1987, ended in Hamburg, F.R. Germany on 2 September 1987, and included 57 scientists and technicians from 19 institutions in 8 European and North American countries (Krause et aI., 1989). The primary objectives were to investigate the modern depositional and oceanographic environment and the paleoceanographic and tectonic development of the eastern Arctic Basin (Augstein, 1987). The Polarstern succeeded in penetrating the Arctic ice as far north as 86' 11' N;
further that any previous multidisciplinary research vesseL. On 3 August, an ice party of four surveyed a large multi-year ice island while the Polar stern maneuvered through the surrounding leads. Large ridges confirmed the strength of this floe; indicating that it had previously withstood
collsions with other floes. Cores were drilled along the perimeter in order to determine thickness, which was on the order of 4 to 6 m. After three hours of coring, a site was chosen near a well ridged edge, in an area accessible to the. Polarstern. This decision was based on the expectation that the preformed ridges would prevent cracking of the ice and act as barriers between the deployed float and neighboring ice floes. Shortly thereafter, work was begun in removing a 1 m diameter ice core approximately 16 m away from the edge, but within range of the cranes aboard the ship. A hot water drill ring developed by U.S. CRREL was used to melt a circle through the ice with hot water provided by a pressurized pump on board the ship (Tucker et aI., 1987). Hydraulic hoses carried the hot water from the
bow of the ship to the ice ring while other station work was being performed off of the stern. Drillng the ice core took over two hours, while the bow crane of the Polarstern removed the 2.5 ton ice plug in one motion.
At 0820 UTC the following day, the actual deployment of the AEDB began. The Polarstern positioned its stern so that the work could be performed
27
within the maximum extension of the rear crane. On the ice, the mooring system was assembled in five 25 m segments. Beginning with the anchor, each section was lowered through the ice hole, secured, and attached to the next section. Finally, the surface float was attached to the last segment and lowered onto four wooden posts positioned in the ice. As a precaution to prevent the yellow metal sphere from absorbing solar radiation in the summer and melting through the floe, the posts would drift away from the buoy without causing damage once the icefloe broke apart. The operation proceeded smoothly, the ice thermistors were subsequently installed within a few meters of the float, and the deployment was
complete.
b. Drift summary ocean regions in 255 days (Fig. 8). During the first four and a half months, it drifted south with the Transpolar Drift pack ice to the Fram Strait, whereupon the buoy's velocity tripled The AEDB travelled over 3900 km through three distinct
as it entered the East Greenland Current. Later, west of Jan Mayen Island, locations became sporadic for 21 consecutive days when the surface float was forced under the sea ice. Upon resurfacing, the buoy was rapidly transported through the Denmark Strait where it was recovered west of Iceland. From 4 August to 21 December 1987, the mooring system was carried by the pack ice from 86.1 to 80.9° N (Table 2). Because of the congestion of the sea ice, over half of the AEDB's journey was spent here, traversing only one-third of the total drift distance. This period was characterized by an average speed of almost 11 cm/s and a maximum speed of 44.8 cm/s. Throughout, the ice island supporting the buoy remained intact, protecting the surface sphere from
damaging ice collsions. In accordance with historical ice drift data, the buoy proceeded in a generally southwesterly direction during the first seven weeks after deployment. In September and October, however, winds forced the
drift southeast; toward the
islands of Svalbard. Fortunately, the system avoided running aground when the course reverted back to the southwest late in October. Just north of 81', in an area where all the polar pack ice begins to squeeze through the Fram Strait, the
drift track became increasingly irregular. The buoy came nearly to a stop on 21 December then immediately accelerated through the narrows.
Between the Fram Strait and the Denmark Strait, the AEDB was
28
Figure 8
Arctic Environmental Drifting Buoy
August 4, 1987
through April
15, 1988
65'N 35'
lO'W
O'
with 2000 m bathymetry contours
29
Table 2
AEDB Drift Regions
Pack Start date latitude (N)
longitude (E)
End date latitude (N)
longitude (E)
Total time (days) distance (km)
Speed (cm/s) minimum
maximum
average std. dev.
East
Ice
Greenland
Denmark Strait
4 Aug 87 86.122 22.047
21 Dec 87
21 Mar 88
80.910 3.660
68.684 -18.150
21 Dec 87
21 Mar 88
15 Apr 88
80.908 3.669
68.684 -18.153
65.305 -31.613
139.3
90.7 1763
25.2 823
0.38 98.00
1.77 101.96 37.76 . 19.5
1321
0.12 44.84 10.97 6.5
22.51
20.8
TOTAL
4 Aug 87 86.122 22.047 15 Apr 88 65.305 -31.613
255.2-3907
0.12 101.96 17.72 16.9
transported by the ice and ocean currents along the east coast of Greenland. Four times in four weeks, the speed of the buoy steadily increased to over 70 cm/s then suddenly decreased to less than 25 cm/s. For 5 days after 21 December, the buoy steadily gained speed, attaining a
peak velocity of 98.0 cm/sec. Over a sea cliff east of Belgica Bank where the ocean depth soars from 2000 to 400 m across less than 40 km, the system began slowing, but accelerated again upon reaching the deeper water. On 2 January 1988, the ice floe containing the float apparently broke up releasing the buoy into the seawater. When this occurred, the ice thermistor chains were torn from the sphere at the same time as the temperature readings temperature) to -2 'C being transmitted from the sphere increased from -18 'C (air
(water temperature). Post recovery calculations showed that the oceanic heat flux had increased to 128 W/m2, and that over 1 m of the icefloe bottom had melted away in the warmer water since deployment (Perovich et aI., 1989).
30
After entering the seawater, the AEDB continued speeding up to 96.6
cm/s. In a three hour period on 4 January, the speed dropped from 91 cm/s down to 32 cm/s concurrent with huge increases in the strain gauge readings (Fig.
9). In some places on the surface sphere, the sensors ~ndicated calculated
pressures in excess of 40,000 PSI, suggesting that it had been compressed by
ice floes. The condition of the sphere upon recovery confirmed that substantial deformation had occurred. The ARGOS transmitting equipment was not significantly damaged by the collsion and stil functioned properly afterwards (at only a slightly diminished reliabilty). On the other hand, readings from the transmitted sphere temperature sensors were no longer reasonable. On the following day, the system reduced its speed to nearly 5 cm/s. By 10 January, the velocity again exceeded 93 cm/s, just prior to plunging
down to 31 cm/sec in another three hour period. The ice pressure effects on the surface float could not be observed at this time, since most of the strain gauge circuits had already reached their full scale limits. The AEDB continued to slow, reversed course five days later, and started heading northeast. The speed of the buoy while heading north peaked at 40.8 cm/s during the three days it drifted in that direction.
After resuming a southwesterly course on 18 January, the AEDB once again sharply accelerated to over 70 cm/s and then reduced speed. From 21 December to 21 January, the mooring system had travelled over 1000 km in the
East Greenland Current, at a pace four times faster than in the pack ice drift. By then it was located at 74° N latitude, having migrated from nearly 81° N.
After 21 January, the location of the float could not be accurately . determined for 11 consecutive days. The number of transmissions from the AEDB patch antennas that were received by the ARGOS satelltes on a single pass were not enough for accurate location determinations. The only remaining useful information that was being transmitted was the battery voltages of the PITs, and that data was being received infrequently. For four successive days in February the signals transmitted by the buoy improved and it was positively relocated. Later, no transmissions at all were received for 6 days, and only one low quality location in 21 days. The surface float may have been pushed below the ice for a portion of this time. After recovery ice was discovered in the sealed hatch designed to protect the watertight connections from stray moisture. Water had to have been forced by pressure past the gasket seal and frozen. Furthermore, in late February and early March only a small distance was covered by the mooring system; the
31
Figure 9
Sphere Temperature and Speed of AEDB Dembe 31. 1987 th Janua 7. 1988
.. 8
l
~
0
120
-5
100
-10
80
-is
60
i~
-20
40
~
-25
20
..~
I
0
-30
3I-De
oi-ran
02-ran
03-ran
04ran
os-ran
06ran
07-ran
_ tepe - sp Strain on AEDB Sphere
Str arund equar: Dembe 31.1987 th Janua 7, 1988 4 3
.. ~ ..i:
2
.5 i
1~
~
1 i ~ 0
-1
-2
3I-De
ol-ran
02ran
03-ran
04ran
os-ran
06ran
07-ran
_ str SA2 _ st SB 1 _ str SC2 -0 str SDl
Str arund bottm: Dem~ 31.1987 th Janua 7,1988 3
2
S
~
-l
.,§
J
..= i
~
1
li
0
-1
-2
3I-De
Oi-ran
02-ran
03-ran
_ str SAI _ strn SB2
04ran
os-ran
_ str Sei
06ran
07-ran
-0 strn SD2
32
volcanic topography below the ocean surface west of Jan Mayen Island may
have impeded its progress. Abruptly during the first week of March, the transmission difficulties pervading the AEDB cleared, and quality locations were received throughout the remainder of the deployment. Initially drifting south toward Iceland, the float nearly stopped on 21 March, and then turned to the southwest as it moved into
the Denmark Strait. Between Iceland and Greenland the drift track circled over itself, and shortly thereafter the buoy's speed began increasing greatly. The buoy travelled at the fastest p~ce throughout its journey in April; reaching its maximum speed on 9 ApriL. Again, large deviations in the speed were evident; the buoy attained its maximum speed of 102 cm/s after drifting at only 0.4 cm/s two days earlier. Only a few miles inside the ice edge, attempts were made by the Icelandic Coast Guard to visually spot the surface float from low flying aircraft, but without success.
c. Recovery operation The AEDB was succes~fully retrieved on 15 April at position 65° 17' N, 31°
38' W in severe weather conditions. An exceptional effort was made by the Captain, crew, and scientists of Marine Research Institute, Iceland and R/S Ami Fridriksson to locate and recover the buoy in such difficult surroundings. Arriving at the approximate position of the AEDB on 14 April, the ice edge was scanned that evening, and most of the next day for the AEDB sphere. By noon on the 15th, it was determined that the buoy was located on the far side of
a large strip of ice. Fortunately, the ice strip broke apart shortly thereafter, allowing the ship to approach a second strip of ice in which the buoy was located. Ten minutes later, the ice had drifted by the sphere, requiring the ship to circle
the ice strip, and retrieve the buoy between ice strips. In 30 knot winds and 3 to 4 m seas, the recovery was difficult but well executed. The recovered mooring system was intact from the sphere down to the SeaData Micrologger. Unfortunately, the recovery terminated at the thimble to which the nylon segment of the mooring was spliced. Consequently, everything below this segment, including the sediment trap, pump, transmissometer, and S4
current meter were lost at sea. The motion of the sphere bobbing in the water prior to deployment indicated that the equipment was missing before the retrieval
operation had begun. 33
The sphere was dented in on all sides, and the handle on top was bent
over. Yellow paint remained only on the very top and bottom of the sphere. Several inches of ice was discovered inside the hatch where watertight connectors interfaced between the cylinder and sphere components, but the watertight compartment housing the electronics was intact and undamaged. The antennas were undamaged in their protective housings mounted on the surface
of the sphere. None of the retrieved mooring hardware exhibited abnormal wear or corrosion. Inside the inner electronics compartment, the PTTs were stil transmitting. The Campbell 21 X Data Logger was stil collecting data, but the valid information ended on January 2, when the ice floe broke up and the thermistor chain separated from the sphere.
Retrieved from the mooring line, both fluorometers were stil flashing. Over 6000 points of hourly data were retrieved from each. The SeaData Micrologger recorded 25,000 samples, but that data was corrupted shortly after deployment by the infiltration of seawater in the bulkhead connection to the sensors. The ADCP recorded data over 7 Mbytes of half-hourly data until March 7 and stopped due to a low battery. The SeaCat unit flooded and collected no data. New from the factory, this unit had not been opened prior to deployment.
34
4. Results Results for each sensor on the AEDB that returned data are presented in
graphical form. Full or partial records over the drift period were recovered from the ARGOS PITs (giving the buoy position), the sphere temperature and strain gauges, the fluorometer packages, the ice thermistor chains, and the ADCP. To faciltate plotting, the drift period of the AEDe was divided into 5 sections of roughly equal duration (Table 3). The start and end dates for each section include a six day overlap with the next section. The. first two sections contain
data from the portion of the drift in the pack ice. The third section includes the transition from pack ice to the East Greenland Current through the Fram Strait. The fourth section is primarily in the East Greenland Current, and the last section includes the passage through the Denmark Strait.
\.
¡,
r
35
Table 3
AEDB Section Data
Date 870804 870927
Start End
Time 1000 2330
Minimum Maximum
Average STD
LonlE)
86.122 84.283 84.277 86.214 85.310
22.047 10.802 8.059 23.844 13.695
SECTION 1 Total Distance = 421.9 km Start End
870928
o
2330
8711'21
Minimum Maximum
Average STD
84.283 82.283 82.283 84.283 83.055
871122 880115
o
2330
Minimum Maximum
Average
82.279 74.426 74.270 82.279 79.349
STD
10.816 12.426 10.816 23.279 17.386.
880116 880310
End Minimum Maximum
o
2330
Average
74.430 70.055 70.055 74.672 71.916
880311
Minimum Maximum
o
70.051
1500
65.305 65.305 70.051 67.831
Average
-23.895 21.400 -1.982 6.905
-24.536 14.686
0.205 28.817 8.946 4.839
-4.371
5.722
-35.753 30.936 0.048 9.990
-39.389 16.357 -4.625 7.998
0.286 39.765 11 .789
6.795
12.423
-11.965 13.064 2.109
-70.955 24.332 -10.466 14.997
-92.540 26.988 -18.476 24.093
0.116 97.997 26.680 23.334
-71.745 38.487 -10.315 11.959
0.979 72.413 13.857 11.502
Ti me = 55 days
-11.326 -16.852 -16.870 -10.505 -13.203
SECTION 4 Total Distance = 658.5 km
880415
Soeed
-11 .341
STD
Start End
V
Time = 55 days
SECTION 3 Total Distance = 1267.8 km Start
U
Time = 54.6 days
SECTION 2 .Total Distance = 560.2 km Start End
(cm/s)
LatlN)
-38.446 34.286 -4.182 7.578
Time = 55 days
-16.852 -31.613 -31.708 -16.836 -22.046
STD
-94.790 56.073 -20.705 21.520
-65.643 28.271
-17.264 14.990
0.376 101.959 32.423 19.061
SECTION 5 Total Distance = 998.6 km Time = 35.6 days ALL SECTIONS
Total Distance = 3907.0 km Time = 255.2 days Average Speed = 15.3 km/day
36
Fig. 10. A histogram giving the number of ARGOS location fixes versus the time ~
difference between consecutive fixes from 0 to 225 min in 1 min intervals is shown. Data includes all 4414 fixes from PTT 8441, over the entire duration of the AEDB drift. The orbital characteristics of the dual satellte system cause the locations to be variable in positioning accuracy and unevenly spaced in time. The data from PTT 8440 is not analyzed here as it amounted to only one-tenth of the information as PIT 8441 and typically was of poorer quality. Service ARGOS provides a quality indication from 0 to 3 with each position determination; quality 3 indicates fixes with one-standard-deviation accuracy of 150 m, quality 2 gives accuracy of 350 m, quality 1 of 1000 m, and quality 0 of greater than 1000 m. Out of the total 4414 locations obtained from PTT 8441, 3928 were of a quality 2 or 3; only 486 fixes were of quality 0 or 1. It can be seen that a roughly equal number of fixes are obtained for time diferences between 0 and 97 min. This distribution is due to the different orbital altitudes of the two satelltes, which cause the period of one satellte's orbit to be approximately one minute longer than the period of the other. The largest proportion (nearly 20%) of fixes have time differences between 98 and 104 min; a time interval that represents the transit interval for a single satellte (101 min). The number of fixes drops off dramatically for time differences greater than 105 min, amounting to only 6% of the total. The secondary peak at about 200 min. results from data obtained between two passes of a single satellte.
i
f
37
Figure 10
Platform Transmit Terminal 8441 20
iso
rI Q)
.es
~ ~
100
-g
e Z
so
o o 10 20 30 40 SO 60 70 80 90 100 no 120 130 140 iSO 160 170 iSO 190 20 210
Time Between Consecutive Reags (mi)
/
38
Fig. 11. Azimuth stereographic projection plots of the drift track of the AEDB: a)
section 1, b) section 2, c) section 3, d) section 4, e) section 5. Locations are plotted every half-hour and connected by line segments. Crosses mark every 96th point (equal to a two day interval), while only every other cross is date
labeled. The raw data is from PTT 8441, and is primarily composed of location fixes possessing an ARGOS quality indication of either 3 (150 m accuracy) or 2
(350 m accuracy). During certain periods, however, lower quality locations were used to fil in large gaps of time without higher quality positions. From 30 January thru 15 March 1988 (in section 4), locations with qualities of 1 (1000 m accuracy) and 0 (greater than 1000 m), were used in the absence of any quality 2
or 3 fixes. In fact, no locations were obtained between 21 and 30 January, and only one location between 8 Februar and 3 March; consequently, these portions
of the drift track are entirely straight-line interpolations. From 16 March thru 1 section 5), quality 1 fixes were used in addition to quality 2 and 3 locations, to add detail to an otherwise rough plot.
April (in
The raw data generated an unequally-spaced time series of locations. Taking into account the curvature of the Earth, a second time sequence was
derived by computing the speed of the buoy from the locations. The speed sequence was divided into subsections and the standard deviation of each was
calculated. Locations that corresponded to speed points that exceeded 3 times the standard deviation for each section, were removed from the original time series. In this manner, 363 questionable locations were eliminated and the resulting series interpolated using a straight-line method to produce a smooth, equally spaced location time series with a half-hour intervaL.
39
Figure 11 a
86.25
8
12
16
24
20
.86. 25 09
86
86
85. 75
85. 75
85.50
85. 50
85.25
85. 25
85
85
84.75
84. 75
84.50
84.50
84.25
84. 25
84 8
12
16
20
24
84
40
Figure 11 b
12
16
84.25.
24
20
84.25 84
81l
83. 75
83. 75
83. 50
83. 50
83.25
83.25
83
83
82.75
82. 75
82.50
82.50 82.25
82
12
16
20
24
82
41
Figure 11 c
-12
-8
-4
o
4
8
42
Figure 11 d
-22
75
-20
-16
-12
-10
75
74
8802 i 7 3
73
72
71
72
I
71
70
70
69
-22
69
-20
10 -1 G
43
Figure 11 e
(! (!
If (! (!
::
C\ i
co C' I
C'
('
I ci
r-
0'
(!
co
(!
r(!
CD
(!
C'
(' If I (!
44
Fig. 12. AEDB speed and East and North velocity time series in cm/s: a) section
1, b) section 2, c) section 3, d) section 4, e) section 5. A positive U represents easterly displacement, while a positive V represents northerly displacement. The U and V time series are the scaled first differences of the location time series calculated as per Figure 11, and filtered through a 7 point triangular filter. The speed time series is the magnitude of the vector formed from U and V. In section 4, extended periods of missing locations generate long segments of constant velocity interpolations.
45
Figure 12a
\
t
C)
~
-c
000000000 o lX lO .q NOlO N .-
(:)as / w:)) paads
(:)as/w:)) n
o 0 0 o 00 lO N (:)as /w:)) /\ 46
Figure 12b
in
N
o N
If ~
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o N
~ U
~O o .. If
0000000 o ro ~ ~ N 0 ..
o tt
o ~ 0 N 0 N I
o 0 0 0 o .. 0 ~ N I
(:Jas/w:J) paads
(:Jas /W:J) n
(:Jas/w:J) A
47
Figure 12c
z
o -c - ""
oN
u w
~O o to
otl
~ o ~Z
000000000 o ro ~ v N 0 ~ N .-
.-
.-
o o 0 ~ 0 N
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48
Figure 12d io
.. o
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Figure 12e
)0
It :: ~ o ",
oN
a:
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o ", 10
N
a:
~
~ ::
It
00..
0
co
0
to
0
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0
N
0 00 ..
0
to
0
N
00.. 00
0 to
0 N
0 N
0 to
I
I
i
i
(~3S/W~) p33dS
(~3S/W~) n
0 0..
(~3S/W~) Â 50
Fig. 13. AEDB sphere temperature time series during sections 1, 2, and 3. Information from only a single temperature sensor of PIT 8441 is shown, since differences between all 6 sensors mounted at separate locations in the sphere were insignificant. The sphere temperature provides a rough indication of the temperature of the surrounding environment, but is not exactly the air temperature. The processed measurements do indicate that the inner surface of the yellow steel shell varied from +10 to -38 'C, and reveal the moment when the float fell into the seawater on 2 January 1988 by a sudden increase of the temperature stabilzing at -2 'C. The plot ends on the following day i when the
sphere became dented and the sensors no longer provided valid data. Like the ARGOS location data, the raw temperature data from the PITs produced a series unevenly spaced in time. A straight-line interpolation method was used to generate an hourly spaced time series. The thermistor electronics were uncalibrated in the lab, and displayed substantial biases from the air
temperature after deployment of the float. Using air temperature data provided by Dr. H. Hoebert of the Meterologicallnstitute of the University of Hamburg from another drifter 550 m away from, but on the same ice floe as the AEDB, the raw values from PIT 8441 were scaled with a correlation factor of 0.994.
51
Figure 13
iU
0
N
It N
00
tl
It
0 N
It N
Z o- -, ~
It ~
-0Z
0N
a.
It L.
0..
It
It .
0..
- ui
0 -
It N
0tl
0
It
':J
~
~O
iU ~O
0-
0 -
It
..0
It
0-
~ 0 ~Z
0 tl
It
0
Ü w
0 N
It N
N
0N
It N
0
0- 0 0.- 0N 0I" 0v 0iO I
I
I
I
i
(8) 'dw~i lOCI.: 52
Fig. 14. The lithium battery voltage providing main power to PTT 8441 : a) sections 1,2,3, b) sections 4, 5. Fluctuations of the voltage are consistent with
fluctuations in the temperature series of Figure 13. The raw battery voltage data from the PTT was unevenly spaced in time, and was interpolated with a straight line to produce an hourly spaced time series. Platform 8440 battery voltage is nearly identicaL.
/r
t
53
Figure 14a
oC" in
0 N
Z O~ - -,
If ~
-0Z
0 N
0-
CL
If W
in
- ui
0 tt
If
0-
in C"
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0 tl
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in
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r-
or-
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o
oN
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r-
o
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o
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54
Figure 14b
0 .-
in
.-
)-
in ~
~
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- a:
~ ~
0 ,.
in
in
C"
a:
.-~
in 0.
o .o
in
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a:
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SlIO/\ lid
~
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~~
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in
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o
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55
Fig. 15. AEDB sphere strain gauge time series for sections 1, 2, and 3: a) strain gauges SA1 and SA2, b) strain gauges S82 and S81, c) strain gauges SC1 and SC2, d) strain gauges SD2 and SD1; e) strain gauges SD2 and SD1 for section 5. Each plot includes the strain sensors from a vertical section of the sphere; the solid lines are from sensors located on the floor, while the" dashed lines are from gauges placed around the equator of the float (Fig. 2). The raw strain data from the PTTs were unevenly spaced in time, and were straight-line interpolated to produce hourly spaced time series. The displayed strain values are zeroed with respect to the strain present when the buoy was deployed on 4 August 1987. Because strain gauges provide valid data only when the material being stressed is stil elastic, any information furnished by these gauges after 4 January 1988 is questionable since the sphere probably was deformed at this time. Most of the gauges went completely off scale immediately afterwards, only PTT 844 sensors SD1 and SD2 continued to
provide data within limits. But because no transmissions were received from PTT 8440 during time section 4, only section 5 data is plotted.
56
-.
In
100
500
-li(/
o
c
;- 300
..i(/
o
c
2. - 1 00
'::r-"""_.. J
-_.~"'
DEe
--'--- ----
,
-_ - I - "'I _ -..,- ..
"¿ 100 ---...'..-I'----.,---i.i-I._,r".----------~r----~-i
c
r: 300
'-,..,-
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I
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c 300
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500
SA2
SA1 -n
ß)
01
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Figure 15b
I-
U
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in
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alal
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l -300~, , ~ , , __ , , , , I.. , I~' ,.n , , , Iu: , I , , "n , , l , ,')¡: , , , , , , ,~~n , , I .\, , , I 10 I I i , ,15 I , , ,20 , , ,j -500, , . __ i:
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61
Fig. 16. Comparison of the speed of the AEDB (top) with the ice and water temperature data (bottom) over the time period 14 December 1987 (day 348) to 2 January 1988 (day 367). The 16 m water temperature series is from the ADCP. The complete sectionalized 16 m series is presented in Figures 15a through 15d. The ice thermistor chains provided the 5.6 and 3.0 m water temperatures, and
the 2.75, 2.50, and 2.25 m ice temperatures. Depths are measured from the surface of the ice.
The ice thermistor data was analyzed by Perovich et al. (1989). Due to a malfunction in the data logger's storage module, information from August 4 to December 14 was lost. However, there was a total of 0.72 m of bottom melting during this period, indicating a time-averaged oceanic heat flux of 14 W/m2. During the time that data was collected, the buoy experienced a rapid
acceleration through the warmer waters of the Fram Strait, attaining speeds as great as 80 km/day. Before the speed up (day 355), the heat flux averaged 7
and no appreciable bottom ablation occurred. During the following 7 days, 0.23 m of the ice bottom melted and the oceanic heat flux increased by a factor of 18 to 128 W/m2. The time series terminates on 2 January, when the ice fragmented. . thermistor chains were tom from the float as the ice floe W/m2,
62
Figure 16 m to cr
cr to cr
:-
0 CD
, . .
, , , . , . , , , ,
..- ...... '.. ,...........
-..".,, :,
~,
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.
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a~n:le~adwai 63
Fig. 17. AEDB fluorometry time series at 10 and 20 m below the surface: a) sections 1 and 2, b) sections 3,4, and 5. The solid line displays information from the instrument located at 10m below the AEDB and the dashed line from the instrument at 20 m. The unfilered data is plotted as a percentage of the full scale value, which is approximately 5 ug/l of chlorophyll a at the high sensitivity
setting (Appendix B), but depends upon the particular type of plankton in the water. Up until 2 January 1988, the 10m fluorometer was actually in 6 to 7 m of
seawater below 3 to 4 m of ice. Ukewise, the 20 m fluorometer was 16 to 17 m
below the icefloe. The record of the deeper fluorometer ends on 18 January due to a hardware malfunction. Biofouling may have gradually reduced the sensitivity of both fluorometers over the course of the deployment.
64
Figure 17a
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it N
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65
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10 m 20 m
20
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Fig. 18. ADCP heading, tilt, and temperature time series: a) section 1, b) section 2, c) section 3, d) section 4. Heading is the output from an EG&G flux gate compass with a stated accuracy of 2.. Heading data were corrected for variation in magnetic declination over the drift track of the AEDB prior to transformation of velocity to geographic coordinates. The plotted heading is uncorrected. Tilt is
from a pair of Humphrey pendulum tilt sensors with a stated accuracy of 1 % and installed with a tolerance of +/- l' over a 10. range. Temperature is measured by a thermistor mounted in the center of the four transducers. The thermistor has a stated accuracy of 0.1 'C over a range from -5 to 45 .C. The raw ADCP records represent an average of 40 samples separated by one second in time. A record is recorded every half hour. Bad points in the raw records were identified by computing the statistics of the first difference of the data with time. Records were de-spiked by eliminating points where the first difference was greater than three times the standard deviation of the first difference. Values were averaged over one hour prior to plotting.
67
Figure 18a
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a.
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vi
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0.
N i
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(Sap)
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(Sap) ll!l
(~ Ssp) dwSl 68
Figure 18b
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Figure 18c
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Figure 18d
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0Q) I
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(Sap) lI1
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(0 Sap) dwai 71
Fig. 19. ADCP battery voltage and transmit current time series: a) section 1, b) section 2, c) section 3, d) section 4. The high voltage input value represents the voltage from the V2 battery pack available for acoustic pulse transmission and for powering the 60 Mb tape recorder. This voltage is expected to be between 14 and 40 volts. The low voltage input value represents the voltage from the V1
battery pack available for powering ADCP logic, memory, and control circuits.
This value is expected to be between 5.5 and 12 volts. The transmit current is a relative measure of the current available at the output of the power amplifier board and is representatiye of the current used to drive each of the four
transducers. This value is adjusted so that a current of 1.7 to 1.8 amps is observed with V2 at 40 volts. The raw ADCP records represent an average of 40 samples separated by one second in time. A record is recorded every half hour. Bad points in the raw records were identified by computing the statistics of the first difference of the
data with time. Records were de-spiked by eliminating points where the first difference was greater than three times the standard deviation of the first difference. Values were averaged over one hour prior to plotting.
72
Figure 19a
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:: ~
o
N N
..
Cl CO
N N
(SlIOA) H-lndui
~.
N
IX
~.
CO
CO
(SlIOA) 1-lndul
00 CO . . Cl
o
N ~ ,. CO o 0
It
.
(sdwc) l!W-X 73
Figure 19b
o
N N
..
00 co
- N N
(SlIOA) H-lndui
~.
N
00 ~ cD cD (SlIOA) l-lndui
00
. 00 co .
o
N ~ " co ci ci (sdwc) llw-X 74
Figure 19c
o.
N N
..
ao cø
- N N
(SlIOA) H-lndui
N ~
ao ~ cD cD (SlIOA) l-lndui
00 cø . . ao
o
N ~ l" cø o 0 (sdwc) l!W-X 75
Figure 19d
aN N
.N N.
00 CO .- .(SlIOA) H-lndui
"'
.-.
N
00 "' ui ui (SlIOA) l-lndui
00 co . . 00
o
N "' " co d d (sdwc) l!W-X 76
Fig. 20. ADCP echo amplitude data for beam 1: a) section 1, b) section 2, c) section 3, d) section 4. A record containing a relative measure of echo amplitude for the 20 range bins of each of the four ADCP beams is recorded every half hour. For the downward facing ADCP deployed on the AEDB the data from the 20 range bins of each beam form a vertical profile of echo amplitude. The raw ADCP tecords represent an average of 40 profiles separated by one second in time. The echo amplitude is monotonically decreasing with increasing range
from the transducers. Hence, the uppermost line on the plots represents the most shallow range bin at 32 m depth and lines with successively smaller echo
amplitude represent increasing depth in 16 m intervals to a maximum depth of
336 m. The large spacing between the upper lines represents an initial rapid decrease of echo amplitude with range due to attenuation and spreading of the acoustic pulse. The closely spaced lower lines indicate little change in amplitude at the furthest ranges where the echo amplitude has decayed almost completely and the amplitude approaches a limiting value representing the instrument noise floor. Bad points in the raw records were identified by computing the statistics of the first difference of the data with time and with depth. Records were de-spiked by eliminating points where the first difference in time or depth was greater than three times the standard deviation of the first difference. Echo amplitude time series at each depth were averaged over 24 hours and decimated by 6 hours prior to plotting.
77
Figure 20a
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o. CD
d in d~ ,.d
in
d N
Cap) apnl!ldwc 040a L wcaq 78
Figure 20b
o.
CQ
ci d It ~d tt
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Cap) 9pnl!ldwc 04:)9 L wC9q 79
Figure 20c
ol..
d It d ~ c: ..
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Cap) apnl!ldwo 040a L woaq 80
Figure 20d
oU).
d in d.. ttd
dN
Cap) epnl!ldwD 040e L wDeq 81
Fig.
21. ADCP echo amplitude data for beam 2: a) section 1, b) section 2, c)
section 3, d) section 4. Description same as for Fig. 20.
1 iF
82
Figure 21 a
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d
CD
d d It d ~ to
It
d N
(ap) epnl!ldwo 040e L woeq 83
Figure 21b
r
d U)
d II d .. d ~
. o N
Cap) epnl!ldwc 040e Z wceq 84
Figure 21c
ò U)
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Ò N
Cap) epnl!ldwc 040e Z wceq 85
Figure 21 d
. o U)
ci ci II ci ~ tt
ci N
Cap) 9pnl!ldwc 04:)9 G wcaq 86
22. ADCP echo amplitude data for beam 3: a) section 1, b) section 2, c) section 3, d) section 4. Description same as for Fig. 20. Fig.
87
Figure 22a
C)
;: -c
ci
~
ci ci It ci ~ ..
. o N
(ap) epnl!ldwD 04:)e £ wDeq 88
Figure 22b
oco.
ò ò ,.Ò II "I
Ò N
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89
Figure 22c
c:
CD
c: \I c: '" c: It
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(ap) 8pnl!ldwc 0408 £ wcaq 90
Figure 22d
d U)
d in d~ ttd
dN
(ap) epnl!ldwc 040e £ wceq 91
Fig. 23. ADCP echo amplitude data for beam 4: a) section 1, b) section 2, c) section 3, d) section 4. Description same as for Fig. 20.
92
Figure 23a
"::
~
ò U)
ò ò ttÒ II '-
Ò N
Cap) epnl!ldwD 040e 'V wDeq 93
Figure 23b
d~
d in d~ ..d
d N
(ap) epnl!ldwc 040e y wceq 94
Figure 23c
ci
~
ci ci II ci ~ It
oN.
(ap) 9pnl!ldwc 0409 y wcaq 95
Figure 23d
c:
CD
ci c: It ci ~ tt
c: N
Cap) epnl!ldwc 040e t wceq 96
Fig. 24. ADCP absolute velocity time series for the east direction: a) section 1, b) section 2, c) section 3, d) section 4. The vertical scale is correct for the uppermost time series which is centered at a depth of 40' m. Each successive time series is offset by -30'.0 cm/s on the vertical scale and, since these data are averaged over 2 depth bins, each successive line is 32 m deeper. Velocity time series at each depth were averaged over 4 hours and decimated by 2 hours prior to plotting.
A record containing radial velocities for the 20' range bins of each of the four ADCP beams is recorded every half hour. For the downward facing ADCP
deployed on the AEDB the data from the 20' range bins of each beam form a vertical profile of velocity. The raw ADCP records represent an average of 40' profiles separated by one second in
time. Bad points in the raw records were
identified by computing the statistics of the first difference of the data with time
and with depth. Records were de-spiked by eliminating points where the first difference in time or depth was greater than three times the standard deviation of the first difference. The four radial beam velocities are combined to form estimates of horizontal and vertical velocities in the instrument coordinate system. These velocities are then transformed to geographic coordinates using output from the tilt and heading sensors in the instrument. At this stage, the horizontal velocities represent the relative velocity between the water and the drifting AEDB. The absolute velocity is estimated by adding the AEDB drift velocity to the observed ADCP velocity at each time step.
97
Figure 24a
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o
a.
l. U1
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ci
.. I
ci
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0N. ..
0.
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. 0 0 N
. 0 ..N
. 0 co
. 0 N
I
I
I
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(s/wo) Ál!OOI9A lSC9
98
Figure 24b
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d(Ø ..
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Figure 24c
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Figure 24d
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ci 0N
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ci ci N
ci N
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i
tl
(s/wo) ,(llOO\9A lS09
101
Fig. 25. ADCP absolute velocity time series for the north direction: a) section 1,
b) section 2! c) section 3, d) section 4. Description same as for Fig. 24.
102
Figure 25a
l-
U
o
c.
~ ~
It ci
~
ci
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00
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ci N
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(s/w:)) Ál!OOI9A l.LlOU
103
Figure 25b
c: ~
c:
c:
c:
I
I
~
co
c: N .I
. 0 co
.-
c: 0 N
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Ó ~
Ó co
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I
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(s /w:)) Ál!:)OI9A 4lJOU
104
Figure 25c
u w o
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ci co
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ci 0N
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105
Figure.25d
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(S/WO) Ál!OOI9A 4LJOU
106
26. ADCP velocity time series with depth average removed, east direction: a) section 1, b) section 2, c) section 3, d) section 4. The vertical scale is correct for the uppermost time series which is centered at a depth of 40 m. Each successive time series is offset by -10.0 cm/s on the vertical scale and, since these data are averaged over 2 depth bins, each successive line is 32 m deeper. Velocity time series at each depth were averaged over 4 hours and decimated by 2 hours prior to plotting. A record containing radial velocities for the 20 range bins of each of the four ADCP beams is recorded every half hour. For the downward facing ~DCP deployed on the AEDB, the data from the 20 range bins of each beam form a vertical profile of velocity. The raw ADCP records represent an average of 40 profiles separated by one second in time. Bad points in the raw records were identified by computing the statistics of the first difference of the data with time. Records were de-spiked by eliminating points where the first difference was greater than three times the standard deviation of the first difference. The four radial beam velocities are combined to form estimates of horizontal and vertical velocities in the instrument coordinate system. These velocities are then transformed to geographic coordinates using output from the tit and heading sensors in the instrument. At this stage the horizontal velocities represent the relative velocity between the water and the drifting AEDB. The velocities plotted in this figure are formed by computing the average velocity for depths between 36 m and 268 m for each time step and subtracting the depth average from the original velocity at each depth. This technique effectively corrects for the relative motion of the buoy through the water, but also removes any component of the absolute velocity that is uniform over the 232 m where the depth average is computed. Fig.
107
Figure 26a
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::
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ci N
ci
ci N
ci
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(sjwo)
ci
ci
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i
ci
Æl!OOI9A lSC9
108
Figure 26b
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d
0~.
CD
d
. 0 to
I
I
I
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(sjwo)
. 0 N
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Ál!OOI9A lSC9
109
Figure 26c
ci N
ci
0N.
ci
ci
ci
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I
I
I
~
co
co
ci
0 .-
ci N
.-
i
(s/wo)
,(l!OOleA lsce 110
Figure 26d
l
in
NZ
~ -.
ci N
ci
ci N I
ci
~ I
ci
ci
I
I
cø
co
ci
0 --
ci N
--
i
(s/wo)
Ál!OOI9A lSC9
111
27. ADCP velocity time series with depth average removed, north direction: a) section 1, b) section 2, c) section 3, d) section 4. Description same as for Fig. 26. Fig.
112
Figure 27a
'-
=: .~
oN.
ci
ci N
~
. o co
II
I
I
I
I
o.
ci
o .-
ci N .-
(sjWO) Ál!OOI9A 4LJOU
113
Figure 27b
dN
d
dN
d~
dto
d co
I
I
I
I
d o ..
. o N ..
(sjwo) Ál!OOI9A 4lJoU
114
Figure 27c
~
in NZ0
dN
0.
dN
0~.
d CD
. 0 co
I
I
I
I
d 0.-
. 0 N
.-
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(sjwo)
Ál!OOI9A 4lJOU
115
Figure 27d
o ..
o N
ci N
ci
ci N
ci
ci
ci
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I
~
(s/wo)
co
co
ci
ci
0..
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Áll0019A 4lJOU
116
Fig. 28. ADCP vertical velocity time series: a) section 1, b) section 2, c) section 3, d) section 4. The vertical scale is correct for the uppermost time series which is centered at a depth of 40 m. Each successive time series is offset by -5.0 cm/s on the vertical scale and, since these data are averaged over 2 depth bins, each successive line is 32 m deeper. Velocity time series at each depth were averaged over 4 hours and decimated by 2 hours prior to plotting. A record containing radial velocities for the 20 range bins of each of the four ADCP beams is recorded every half hour. For the downward facing ADCP deployed on the AEDB, the data from the 20 range bins of each beam form a vertical profile of velocity. The raw ADCP records represent an average of 40 profiles separated by one second in time. Bad points in the raw records were identified by computing the statistics of the first difference of the data with time. Records were de-spiked by eliminating points where the first difference was greater than three times the standard deviation of the first difference. The four radial beam velocities are combined to form estimates of horizontal and vertical velocities in the instrument coordinate system. These velocities are then transformed to geographic coordinates using output from the tilt and heading sensors in the instrument.
117
Figure 28a
e"
::
.:
d-
d
d d d I d INit" I I
din
dto
I
I
(s /w:t) Ál!:tOI9A ID:t!l-9A
11S
Figure 28b
d..
d
d d d d .. N If I I I i~
d an
dU)
I
I
(s/w:i) Áll:iOI9A IO:i!l-9A
119
Figure 28c
d-
d
d d d d Nit. I I I i
d in
d
I
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CD
(s/w~) ¡(l!~OI9A ID~!lJ9A .
120
Figure 28d
d..
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d d d d .. N Jo I I I i~
d It
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CD
(s/wo) Ál!OOI9A looH.J9A
121
Appendix A: Campbell data logger program
~
Program Table 1
01 : 01 :
5400.0 P89 01: 0001
02:04
1.5 hour table execution interval If X compared to F (to sample at 6 hour rate) Location #1 for X
If X~ F F = 3.000
03: 3.000 02 : 03 : 04 : 05 :
04:30
P32 01: 0001 P86 01: 00 P94 P30
Then Do
Increment input location Destination location #1
Do
Goto end of program table
Else Load fixed data
F = 0.000
01 : 0.000
06 :
02: 0001 P10 01 : 0002
07 :
P89 01 : 0002
Destination location #1
Store battery voltage Destination location #2 If X compared to F (to end if battery is low) Location #2 for X
If X~ F F = 9.7000 Goto end of program table
02: 04 03: 9.7000
04:00 08 :
P20
01: 01 02: 01
09 :
P87 01: 00 02: 0032
10 :
P22 01: 01
02: 0001 03: 0000 04: 5000.0 11 :
P05 01: 01
02: 14
No delay 32 iterations Excitation with delay (clock) Excitation channel 1
Excite for .01 seconds No delay after excitation Excitation = 5000.0 mV Measure AC conductivity (thermistors 1 to 32) 1 repetition 500 mV full scale; fast integration time Single ended channel 1
04:02
Excitation channel 2 Excitation = 500 mV Starting destination location #2 (indexed)
06: 0002C
07: 1.000 08: 0.000 P95 P20 01: 00 02: 01
14 :
Digital control port 1
Loop
03: 01
05: 0500
12 : 13 :
Set port (to enable AM32) Set high (5 V)
P05 01: 03 02: 14 03: 02 04: 03 05: 0500
Multiplier * 1
Zero offset End loop Set port (reset AM32) Set low (0 V) Digital control port 1
Measure AC conductivity (thermistors 33 to 35) 3 repetitions
500 mV full scale; fast integration time Start at single ended channel 2 Excitation channel 3 Excitation = 500 mV
122
06: 0034
Starting destination location #34
07: 1.000 08: 0.000 15 :
P59
16 :
02: 0002 03: 1.0000 P59
Multiplier * 1
Zero offset Compute block resistances (x/(1 - x)) for 1 to 32 01 : 35 35 repetitions
01: 01
02: 0034 17 :
03: 1.0040 P59
18 :
02: 0035 03: .9830 P59
01: 01
Starting destination location #2 Multiplier * 1.0000 ohm Vishay Compute resistance for 33 1 repetition Destination location #34 Multiplier * 1.0040 ohm resistor Compute resistance for 34 1 repetition Starting destination location #2 Multiplier * .9830 ohm resistor Compute resistance for 35
01: 01
02: 0036 03: .9940 19 : P86 01: 10 20 : P77 01: 0110 21 : . P70 01: 35 02: 0002 22: P95
1 repetition
Starting destination location #2 Multiplier * .9940 ohm resistor Do (to enable output) Set flag 1 0
Real time Store day, hour-minute Sample (to store data in SM64) 35 repetitions Starting location #2 End table execution
01 : 02 :
01
Out~ut options M64 enabled
02
9600 baud
05 : 05 : 05 :
87
*4
Set/display time
*5
xxxx HH:MM
Year . Juiian day Hours:Minutes Log data
*0
*A
01 : 02 : 03 : 04 :
0036 0036 19280 0809
01 : 02 : 03 :
1664.0 33080 52865
Memory Allocation Input storage locations Intermediate storage locations Final storage locations in 21 X
Remaining program memory (bytes)
Signatures
*B
Program memory EPROM No. 1 EPROM NO.2
123
Appendix 8: Fluorometer and data logger tests Prior to deployment, laboratory tests were conducted on the fluorometer and data logger packages in order to determine the validity of the data that would be recorded. Using air as a constant fluorescent medium, hourly sampling was conducted using 1 and 3 s time constant settings in the fluorometer, while varying the warmup and averaging parameters in the data logger. These tests showed that a 32 sample average after 11 s warmup with 1 s time constant was comparable to an 8 sample average after a 20 s warmup with a 3 s time constant, as expected. In both cases, the standard deviation of recorded voltage was less than 0.005 V; within the resolution of the fluorometer at the high
sensitivity setting. As a result, precision could be maintained while reducing the battery requirements, since the fluorometer needs to be provided with power for a shorter duration using the 1 s time constant (17 versus 24 s). One test simultaneously determined the Iinearities of both the fluorometer and data logger in a single package. With the fluorometer immersed in one liter of ordinary filtered seawater, a solution containing a phytoplankton culture was added to íhe seawater in discrete microliter increments while the data logger
recorded the voltage output of the fluorometer. Concurrently, readings were being manually recorded from a DVM connected in parallel to the data logger. Four multipoint comparisons (two per fluorometer package) of the amount of
added chlorophyll solution to fluorometer voltage outputs (as indicated by the DVM) produced a straight line relationship with a correlation factor of 0.9997. Similar comparisons between the DVM reading and data logger values correlated
to 0.9999. However, due to a slight mismatching of impedances between the fluorometers and data loggers, the latter comparison also indicated positive bias shifts in the voltage value recorded in the loggers' memory of 66 mV in one unit and 130 mV in the other. These offsets were subtracted from the raw data when converting the retrieved records in the data loggers to fluorometer voltages. The fluorometers were roughly calibrated to a known concentration of
chlorophyll s, composed of a solution of dried spinach and 100 ml of acetone, using the manner described by Strickland and Parsons (1972). Readings obtained by the fluorometer package were compared to the calculated chlorophyll values. Due to the biases in the data loggers and possible slight imperfections in the optical components of the fluorometers, the shallow and deep fluorometers displayed different full scale values. The shallow package attained full scale at 3.9 ug/l chlorophyll a, while the deeper unit reached full scale at 5.1 ug/l.
124
Appendix C: Schedules for sediment trap and micro-filter pump Micro-filter Pump
Sediment Trap
Sample test
start
Date 4 Aug 87
4Aug
Time 7:50
18:00
Filter
test 1
2 1
24 Aug
18:00
2
13 Sept
18:00
3
3 Oct
18:00
4
23 Oct
18:00
5
12 Nov
18:00
6
1 Dec
18:00
7
22 Dee
18:00
8
11 Jan
18:00
9
31 Jan
18:00
10
20 Feb
18:00
11
11 Mar
18:00
12
31 Mar
18:00
13
20 Apr
18:00
Date 4 Aug 87
4Aug 19 Aug
Time 7:10
18:00 18:00
3
3 Sept
18:00
4 5 6
18 Sept
18 Oct
18:00 18:00 18:00
7
2 Nov
18:00
8 9 10
17 Nov 2 Dec 17 Dec
18:00 18:00 18:00
11
3
Oct
1 Jan 88
18:00
12 13 14
16 Jan 31 Jan
15 Feb
18:00 18:00 18:00
15
1 Mar
18:00
16 17 18
16 Mar 31 Mar 15 Apr
18:00 18:00 18:00
19
30 Apr
18:00
125
References Aagaard, K., A synthesis of the Arctic Ocean circulation, Rapp. P.-v. Réun. Cons. int. Explor. Mer, 188, 11-22, 1989. Andrews, J.T., Climatic evolution of the eastern Canadian Arctic and Baffin Bay
during the past three millon years, Philosophical Transactions of the Royal Society of London, Series B: Biological Sciences, 318, 645-660, 1988. Augstein, E., coordinator, ARKTIS iV (1-3) gemeinsam mit dem Forschungsflugzeug POLAR 2, Expeditionsprogramm Nr. 10, Alfed Wegener Institute for Polar and Marine Research, 54 pp., 1987. Colony, R., Nansen's Luck, J. Geophys. Res., in press, 1990.
Gorshkov, S.G., ed., Arctic Ocean, Vol. 3 of World Ocean Atlas, Pergamon Press, Oxford, 189 pp., 1983. Hibler, W.O., and J.E. Walsh, On modeling seasonal and interannual fluctuations of Arctic sea ice, J. Phys. Oceanogr., 12, 151 4-1523, 1 982.
Honjo, S., Particle Fluxes and Modern Sedimentation in the Polar Oceans,
Chapter 12 in Polar Oceanography (W.O. Smith, Jr., ed.), Academic Press, New York, in press, 1990. Johannessen, O.M., W.D. Hibler, P. Wadhams, W.J. Campbell, K. Hasselmann, i. Dyer, and M. Dunbar, MIZEX, A Program for Mesoscale Air-Ice-Ocean Ice Zones: II. A Science Plan for Interaction Experiments in Arctic Marginal
Ice Zone Experiment in the Fram Strait/Greenland Sea: 1984, Cold Regions Research and Engineering Laboratory Special
a Summer Marginal
Report 83-12, Hanover,New Hampshire, 47 pp., 1983. Jones, E.P., D. Nelson and P. Treguer, Chemical Oceanography, Chapter 7 in Polar Oceanography (W.O. Smith, Jr., ed.), Academic Press, New York, in press, 1990.
126
Krause, G., J. Meinke, and J. Thiede, Scientific Cruise Reports of Arctic Expeditions ARK IVI1, 2 & 3, Reports on Polar Research 56, Alfed Wegener Institute for Polar and Marine Research, 150 pp, 1989.
Maykut, G.A, Large-scale heat exchange and ice production in the central Arctic,
J. Geophys. Res., 87, 7971-7984,1982. Nansen, F., Farthest North, Vol. I, Westminster, Archibald Constable and
Company, 1897. ÖSlund, H.G., and G. Hut, Arctic Ocean Water Mass Balance from Isotope Data, J. Geophys. Res., 89, 6373-6381, 1984.
Perovich, D.K., W.B. Tucker II, and R.A Krishfield, Oceanic heat flux in the Fram Strait measured by a drifting buoy. Geophys. Res. Let., 16,995-998, 1989. Strickland, J.D.H. and T.R. Parsons, A Practical Handbook of Seawater Analysis, Bulletin 167, 2nd edition, Fisheries Research Board of Canada, Ottawa, 310 pp, 1972.
Thorndike, AS., and R. Colony, Arctic Ocean Buoy Program Data Report 19 January 1979 - 31 December 1979, Polar ScienÖe Center, University of
Washington, Seattle, 131 pp., 1980. Tucker, W.B. III and J.W. Govoni, A Portable Hot Water Ice DrilL. Cold Regions
Science and Tech., 14,57-64,1987. Untersteiner, N., The Geophysics of Ice, Plenum Press, New York, 1196 pp., 1986.
Untersteiner, N., and AS. Thorndike, Arctic data buoy program, Polar Record,
21,127-135,1982. Vinje, T. and O. Finnekasa, The Ice Transport through the Fram Strait, Skrifter
Nr. 186, Norsk Polarinstitutt, Oslo, 39 pp., 1986.
127
Wadhams, P., The Ice Cover, Chapter 2 in The Nordic Seas (B.G. Hurdle, ed.),
Springer-Verlag, Berlin, 777 pp., 1986.
Weeks, W.F., and S.F. Ackely, The growth, structure, and properties of sea ice, CRREL Monograph 82-1 , Cold Regions Research and Engineering
Laboratory, Hanover, New Hampshire, 130 pp., 1982.
128
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REPORT DOCUMENTATION 11. REPORT NO.
PAGE WHOI-90-02
3. Recipient's Accsssion No.
2.
4. Title and Subtite
5. Report Date
The Arctic Envionmenta Dritig Buoy (AEDB)
Janua,
Report of Field Options and Results August. 1987 - Apri
1990
6.
1988
7. Author(s)
8. Perfrming Organization Rept. No.
WH0I90-02
Susumu Honjo, Richad Krshfield, Albert Plueddemann 9. Perfrming Organization Name and Address
10. ProjectaskIork Unit No.
The Woods Hole Oceaogrphic Institution Woods Hole, Machustt 02543
11. Cotract(C) or Grant(G) No. (C) ONR Number
NOOOI4-87, 88,
(G) 89,J-1288 12. Sponsoring Organizaion Name and Address
13. Type of Report" Period Covered Technica Report
Fundig was provided by the Offce of Naval Reseh 14.
15. Supplementary Not..
This report should be cited as: Woo Hole Oceaog. lost Tech. Rept., WHOI-90-02. 16. Abstract (Umlt: 20 word) There are strong reons to gather data on pola oceaogrphy and cliatology in rea tie using fully automate, unattended intrentation systems for long period; pacully dwing the inaccessible winter months when movig ice is extremely hazardous.
We deployed an Artic Envirnmenta Drftng Buoy (AEDB) on 4 August 1987 at 86°7' N, 22° 3' E off of the FS Polarstern on a lage 3.7 m thck ice island. The AEDB consiste of2 major components: a 147 cm dieter surace float housing ARGOS trsmitters and a data logger for ice-profilig thermistors, and a 125 m long moorig line atthed to the sphere and fed though aIm dieter ice hole.
Along the moorig were deployed 2 fluorometers, conductivity and temperatue loggers, an Acoustic Doppler Curent Profùer (ADP),
a curent meter, and a time-series seent trp/microfùter pump/trsmissometer unit. The AEDB proeeded southwesterly with the Traspola Drft at an average spd of 15.3 km/day, with a maxum sp of 88.8 kmday. On 2 Janua 1988, the AEDB droppe into the wate while passing thugh the Fra Strt and for the remaining drft period was either fr-floatig on the water surace or underneath the sea ice. Thughout this period, the trsmitters onboard successfully trsmitted position, temperatue, and strn caused by ice on the sphere. Although the sedent trp package was lost durg the drft. valuable data was collected by the other instrments thoughout the experiment. The ice thermistor data was use to determine ocanic heat flux, while contiuous ADCP observations over the Yermak Plateau provided a weath of information for understading internal waves in the ice-covered ocea. The buoy was recovered .by the Iceladic shipR/S Ami Fririksson on 15 Aprl
1988 at
65° 17' N, 31° 38' W, off
southeatern Greenland, completing 3,900km
of drft in 255 days. Wear in the process of constrctig the next automated stations which are planned for deployment in both the nort
and south polar regions in 1991-92.
17. Document Analysis a. Decrlptore
1. transpla drt 2. ice ocean environment
3. ADCP b. Identifiers/Open-Ended Terms
c. COSATI Field/Group
18. Availabilty Statement
19.. Securit Class (This Report)
UNCLASSIFIED
Approved for publication; distrbution unlimited.
20. Seurity Class (This Page)
(See ANSI-Z39.18)
S.e Instructions on Reverse
21. No. of Pages
128 22. Price OPTIONAL FORM 272 (4-77) (Formerly NTIS-35)
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